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不足する

B1 verb #3,500 most common 9 min read

不足する

fusoku suru Top 3,500

Practice it Examples Notes & Tips 不足する in 30 Seconds

Explanation 不足する in your Level:

At the A1 level, you can think of 不足する (fusoku suru) as a more 'grown-up' way to say 'not enough'. You probably already know the word nai (not there) or tarinai (not enough). Fusoku suru is used when you want to talk about things like sleep or food in a slightly more serious way. For example, if you don't sleep enough, you can say 'Suimin (sleep) ga fusoku shite iru'. It's like saying 'I have a sleep shortage'. Even at this early stage, try to remember the two kanji: 不 (not) and 足 (enough). This will help you read signs in Japan that might say things like 'Water shortage' (Mizu-fusoku). Just remember to use 'ga' before it and 'shite iru' after it to describe how you feel right now.

For A2 learners, 不足する becomes a useful tool for describing your daily life and health. You can use it to explain why you are tired (sleep shortage) or why your cooking didn't turn out well (lack of ingredients). At this level, you should start noticing it in simple news headlines or health posters. It's often paired with nouns to make compound words. For example, undou-fusoku means 'lack of exercise'. Instead of using long sentences, Japanese people often just combine the noun and 'fusoku'. When you go to a doctor, they might ask if you are yasai-fusoku (lacking vegetables). Practice using it with the ~te iru form to describe your current habits, like 'Saikin, yasai ga fusoku shite imasu' (Lately, I'm not getting enough vegetables).

At the B1 level, you should be able to use 不足する in professional and academic settings. This is where the word really shines. You can use it to describe a lack of 'keiken' (experience) in a job interview or a lack of 'setsumei' (explanation) in a presentation. You should also understand that it is an intransitive verb. This means you don't 'do' the lacking; the subject simply 'is' lacking. For example, 'Yosan (budget) ga fusoku suru' means the budget falls short. You will also encounter it in the past tense 'fusoku shita' to describe why something failed. 'Junbi (preparation) ga fusoku shita node...' (Because preparation was insufficient...). Start using it to sound more objective and professional in your speech and writing.

At the B2 level, you should master the nuances between 不足する and its synonyms like ketsujo suru or ketsubou suru. You will use 不足する to discuss societal trends, such as the jinzai-fusoku (talent shortage) in the tech industry or shoushi-koureika (declining birthrate) leading to a labor shortage. You should be comfortable using it in complex sentence structures, such as conditionals (fusoku sureba) and as a noun modifier (fusoku shite iru riyuu - the reason it is lacking). You'll also see it in formal business documents, often in the humble form fusoku shite orimasu. At this level, you should be able to explain exactly why a resource is insufficient using logical connectors like ni tomonai (along with) or ni yori (due to).

For C1 learners, 不足する is a precise instrument for analysis. You will use it in essays to critique policies or scientific findings. You might discuss the ronriteki na fusoku (logical insufficiency) of an argument or the toukeiteki na fusoku (statistical insufficiency) of a data set. You should be able to use it in its various forms fluently, including nominalized versions like fusokubun (the portion that is lacking). You will encounter it in high-level literature and editorials where the 'lack' being discussed is often abstract, such as a 'lack of imagination' or a 'lack of historical awareness'. At this stage, your focus should be on the collocations—which adverbs and nouns most naturally pair with 不足する in academic and literary registers.

At the C2 level, you have a native-like grasp of 不足する. You understand its historical weight and how it differs from more poetic or archaic terms for 'lack'. You can use it with absolute precision in high-stakes environments, such as legal contracts or philosophical debates. You might analyze how the word's usage has shifted in modern Japanese compared to Meiji-era texts. You can effortlessly switch between 不足する and its more intense counterparts like ketsubou or toboshii to create specific rhetorical effects. Your mastery extends to understanding the subtle social implications when a leader uses this word—whether they are taking responsibility for a 'lack' or attributing it to external factors. You can use the word to navigate the finest nuances of Japanese professional and intellectual life.

Practice it Examples Notes & Tips

不足する in 30 Seconds

A formal Suru-verb meaning 'to lack' or 'be insufficient' compared to a standard.
Commonly used for health (sleep/exercise), business (budget/staff), and social issues (resources).
Usually pairs with the particle 'ga' and is most often used in the continuous form 'shite iru'.
More objective and professional than the casual alternative 'tarinai'.

The word 不足する (fusoku suru) is a cornerstone of formal and semi-formal Japanese, representing the concept of 'insufficiency' or 'lacking'. At its core, it is a Suru-verb derived from the noun fusoku (不足). In the Japanese linguistic landscape, this word bridges the gap between everyday physical needs and complex societal deficits. When you use 不足する, you are not just saying something is 'missing'; you are stating that the quantity or quality of a specific resource does not meet the required threshold for a particular purpose.

Semantic Range: It covers everything from biological needs like sleep and vitamins to abstract concepts like experience, talent, or evidence. Unlike the more colloquial 'tarinai', this word carries a weight of objectivity, often used in reports, medical diagnoses, and news broadcasts.

最近、運動が不足する傾向にあります。 (Lately, there is a tendency to lack exercise.)

The kanji composition is vital for understanding. The first character 不 (fu) means 'non-' or 'not', acting as a prefix for negation. The second character 足 (soku/ashi) literally means 'foot', but in this context, it refers to 'sufficiency' or 'reaching a standard'. Historically, having enough to 'stand on' or 'reach' implied adequacy. Therefore, 不足 is the state of 'not reaching' the necessary level. This objective nuance makes it the preferred choice when discussing statistics or health conditions.

Register and Tone: While 'tarinai' might be used if you are short 100 yen at a convenience store, 'fusoku suru' would be used in a government report discussing a 100-million yen budget deficit. It sounds professional, serious, and precise.

ビタミンが不足すると、肌荒れの原因になります。 (When vitamins are insufficient, it causes skin irritation.)

In modern Japan, the word is frequently paired with societal issues. You will hear about jinzai-fusoku (labor shortage) or suimin-fusoku (lack of sleep). These are not just casual observations; they are recognized conditions. By using this verb, you signal that you are looking at the situation through a lens of requirements and standards. It is less about 'feeling' like you want more and more about the 'reality' that there is not enough.

Grammatical Flexibility: As a Suru-verb, it can be conjugated into various forms: fusoku-shita (past), fusoku-shite-iru (present progressive), and fusoku-sureba (conditional). This allows it to function as the predicate of complex logical sentences.

Mastering 不足する requires understanding its relationship with particles and its most common grammatical patterns. Typically, the resource that is lacking is marked with the particle が (ga). This identifies the subject of the insufficiency. For example, in 'Water is insufficient,' water is the subject: 水が不足する. However, in contexts where you are comparing items or stating a general topic, は (wa) may be used.

The '~te iru' State: Crucially, when describing a current condition, Japanese speakers almost always use the form 不足している (fusoku shite iru). If you say 'fusoku suru', it often sounds like a general rule or a future prediction rather than a description of the present moment.

この国では、深刻な食料が不足している。 (In this country, food is seriously lacking.)

When used to modify a noun, you can use the past tense 不足した (fusoku shita) or the present 不足している (fusoku shite iru). For instance, 'a lack of experience' can be rendered as 経験の不足 (noun form) or 経験が不足している状態 (verb phrase modifying a noun). In academic writing, you might see 不足する事態 (a situation where things become insufficient).

Combining with Adverbs: Common adverbs used with this verb include 著しく (ichijirushiku - remarkably), 致命的に (chimeiteki ni - fatally/critically), and 多少 (tashou - somewhat). These add precision to the level of deficiency being discussed.

準備が不足していたため、計画は失敗した。 (Because preparation was insufficient, the plan failed.)

Another important usage is in the conditional form. 不足すれば (fusoku sureba) or 不足すると (fusoku suru to) are used to describe consequences. 'If the budget is insufficient, we will stop the project' becomes 予算が不足すれば、プロジェクトを中止します. This logic is common in business contracts and technical manuals. The verb effectively sets a threshold that, when not met, triggers a specific outcome.

Passive and Causative: Passive forms (fusoku sareru) are rare because 'lacking' is a state rather than an action performed by an agent. Causative forms (fusoku saseru - to cause a lack) are also uncommon; usually, one would use 'fusoku wo maneku' (to invite a lack) instead.

If you turn on a Japanese news program (like NHK), you are almost guaranteed to hear 不足する within the first fifteen minutes. It is the standard term for reporting on social crises. Whether it is a 電力不足 (denryoku fusoku - electricity shortage) during a heatwave or a 人手不足 (hitode fusoku - labor shortage) in the service industry, the verb form 不足する describes the ongoing trend of these deficits.

The Workplace Context: In a Japanese office, your manager might say, '説明が不足しています' (Your explanation is insufficient). This is a polite but firm way of saying you need to provide more detail. It sounds more professional and less personal than saying 'You didn't explain enough'.

会議の資料が不足しているので、コピーしてきます。 (The meeting materials are insufficient, so I will go make copies.)

In medical and health contexts, doctors use this word to discuss lifestyle habits. 睡眠不足 (suimin fusoku) and 運動不足 (undou fusoku) are household terms. A doctor won't just say you don't sleep enough; they will say 睡眠が不足しています. This framing makes the lack of sleep sound like a clinical deficiency that needs to be addressed, much like a vitamin deficiency.

Education and Self-Improvement: Teachers use it to evaluate students' work. '努力が不足している' (Effort is lacking) is a common piece of feedback on report cards. It focuses on the gap between the student's current effort and the expected standard.

今の私には、彼を支える経験が不足している。 (Currently, I lack the experience to support him.)

Finally, you will encounter this in supermarkets or during natural disasters. If there is a 米不足 (kome-fusoku - rice shortage), signs will be posted saying 在庫が不足しております (Stock is currently insufficient). The humble form しております is used here to maintain customer service etiquette while delivering bad news about availability.

One of the most frequent errors for English speakers is confusing 不足する (fusoku suru) with 足りない (tarinai). While both mean 'not enough', they are not always interchangeable. Tarinai is an adjective-like verb that is much more common in casual, spoken Japanese. If you are at a dinner table and want more water, saying 水が不足している sounds bizarrely like a scientific report. You should say 水が足りない.

The 'Amount' vs 'State' Error: Learners often try to use 'fusoku suru' for simple counting. For example, 'I need two more chairs' should not use 'fusoku suru'. Instead, use 'ato futatsu tarinai'. 'Fusoku suru' is for the general state of the resource pool.

❌ 100円が不足しています。
✅ 100円足りません。 (I'm short 100 yen.)

Another mistake is the misuse of particles. Because English says 'I lack experience,' learners often try to use an object particle: ❌ 経験を不足する. This is incorrect. In Japanese, the thing that is lacking is the subject, so you must use が (ga): ✅ 経験が不足する. The lack is something that is happening 'to' the resource (it is falling short), not something you are doing to it.

Confusion with 'Kakeru' (欠ける): 'Kakeru' means something is 'chipped' or a specific part is missing from a whole (like a piece of a puzzle). 'Fusoku suru' refers to the total volume or quantity being too low. If a team is missing one specific person, use 'kakeru'. If the team doesn't have enough people in general, use 'fusoku suru'.

❌ 彼は才能が不足する。
✅ 彼は才能が不足している。 (He lacks talent.)

Finally, do not confuse 不足 (fusoku) with 不満足 (fumanzoku - dissatisfaction). While they share the 'fu' prefix, fusoku is about quantity/sufficiency, while fumanzoku is about the emotional state of being unhappy with something. You can have a 'fusoku' of food without being 'fumanzoku' (perhaps you are fasting), though usually, one leads to the other!

Japanese has several ways to express the idea of 'not enough', each with its own nuance. Understanding these alternatives will help you choose the right word for the right situation. The most common alternative is 足りない (tarinai), which we've discussed as the casual, everyday counterpart to 不足する. It is versatile and safe for almost any spoken situation.

欠乏する (Ketsubou suru): This is a much stronger version of 'fusoku suru'. It implies a severe, perhaps life-threatening 'destitution' or 'scarcity'. It is used for 'famine' (shokuryou-ketsubou) or a total 'lack of vitamins' in a medical sense. Use this only when the situation is extreme.

砂漠では水分が欠乏する。 (In the desert, moisture is severely scarce.)

Another professional term is 欠如する (Ketsujo suru). This is specifically used for abstract qualities that should be present but are entirely missing. Common examples include 常識の欠如 (lack of common sense) or 責任感の欠如 (lack of a sense of responsibility). While 不足 suggests there is some but not enough, 欠如 often implies it is missing entirely.

品切れ (Shinagire): Used specifically in retail to mean 'out of stock'. If a store is 'fusoku' of an item, they might have a few left but not enough for everyone. If they are 'shinagire', they have zero.

彼の計画には具体性が欠如している。 (His plan lacks concreteness.)

Finally, consider 乏しい (toboshii). This is an i-adjective meaning 'scarce' or 'poor in'. It is often used for natural resources or knowledge. 経験が乏しい (poor in experience) is very similar to 経験が不足している, but toboshii feels more descriptive and literary, whereas fusoku suru feels more like a statement of fact.

Summary of Nuance: 1. 足りない: General/Casual. 2. 不足する: Objective/Formal. 3. 欠乏する: Severe/Extreme. 4. 欠如する: Abstract/Missing entirely. 5. 乏しい: Descriptive/Literary.

How Formal Is It?

Fun Fact

The kanji for 'foot' (足) is used for 'sufficiency' because in ancient times, the length of a foot was a standard unit of measurement. If something didn't 'measure up' to the foot, it was 'fusoku'.

Pronunciation Guide

UK /fu.so.ku.su.ru/

US /fu.so.ku.su.ru/

Japanese is a pitch-accent language, not a stress-accent language. In 'fusoku', the pitch starts low on 'fu' and rises on 'so', then stays level or drops slightly.

Rhymes With

Kizoku (aristocracy) Gozoku (powerful family) Kozoku (royal family) Shizoku (clan) Zoku-zoku (shivering) Musoku (unemployed - rare) Kyousoku (standard) Hizoku (vulgar)

Common Errors

Pronouncing 'fu' like an English 'f' with teeth on lips (it should be a bilatbial fricative).
Stress-accenting one syllable like 'fu-SO-ku' (keep it even).
Mispronouncing 'soku' as 'sow-ku' (the 'o' is short).
Over-emphasizing the 'u' in 'suru' (it's often very short).
Confusing the pitch with 'fuzoku' (attached/affiliated).

Difficulty Rating

Reading 3/5

The kanji are common but the 'soku' reading for 'foot' in this context needs to be learned.

Writing 3/5

Writing 不 and 足 is relatively easy for intermediate learners.

Speaking 2/5

The pronunciation is straightforward, but remember to use 'shite iru'.

Listening 2/5

Very common in news and formal announcements.

What to Learn Next

Prerequisites

不 (not) 足 (foot/enough) する (to do) 足りる (to be enough)

Learn Next

欠乏する (to be scarce) 欠如する (to lack abstractly) 補う (to supplement) 満たす (to satisfy)

Advanced

供給 (supply) 需要 (demand) 均衡 (balance) 過剰 (excess)

Grammar to Know

Suru-verbs (Noun + する)

不足 + する = 不足する

The particle 'ga' for subjects of state

水が不足する。

Te-iru for ongoing states

不足している。

Tame/Node for reasons

不足しているため、できません。

Gimi (tendency to...)

不足気味だ。

Examples by Level

水が不足しています。

Water is insufficient.

Uses 'ga' to mark the subject and 'shite imasu' for current state.

時間が不足しています。

Time is insufficient.

Simple subject-verb structure.

お金が不足しました。

Money was insufficient.

Past tense 'shita' indicates a completed state of lack.

野菜が不足していますか？

Are vegetables insufficient (in your diet)?

Question form using 'ka'.

睡眠が不足すると、眠いです。

When sleep is insufficient, I am sleepy.

Conditional 'to' used for general cause and effect.

果物が不足しています。

Fruit is lacking.

Describing a current physical lack.

塩が少し不足しています。

Salt is a little insufficient.

Adverb 'sukoshi' modifies the degree of lack.

本が不足しています。

Books are insufficient.

Plurality is implied by context.

最近、運動不足しています。

Lately, I'm lacking exercise.

Compound noun 'undou-fusoku' used as a verb.

この町は公園が不足している。

This town lacks parks.

Describing a geographic or social condition.

準備が不足していたので、負けました。

Because preparation was insufficient, we lost.

Using 'node' to show reason.

ビタミンが不足すると、病気になります。

When vitamins are insufficient, you get sick.

General truth using conditional 'to'.

経験が不足しているけれど、頑張ります。

Although I lack experience, I will do my best.

Using 'keredo' for contrast.

電気が不足する可能性があります。

There is a possibility that electricity will be insufficient.

Noun 'kanousei' following the plain verb form.

材料が不足しているので、買わなければなりません。

Because ingredients are insufficient, I must buy some.

Combining 'node' with 'nakereba narimasen'.

説明が不足していて、わかりませんでした。

The explanation was insufficient, so I didn't understand.

Te-form used for cause and effect.

このプロジェクトは予算が不足している。

This project lacks budget.

Professional context for 'yosan'.

専門的な知識が不足していると感じます。

I feel that specialized knowledge is lacking.

Using 'to kanjiru' (to feel that...).

人手が不足しているので、新しい人を採用します。

Because we lack manpower, we will hire new people.

Common business term 'hitode-fusoku'.

彼の説明は、具体性が不足している。

His explanation lacks concreteness.

Abstract noun 'gutaisei'.

情報が不足しているため、判断できません。

Because information is insufficient, I cannot make a judgment.

Formal reason marker 'tame'.

もし資金が不足すれば、銀行から借ります。

If funds become insufficient, we will borrow from the bank.

Hypothetical conditional 'sureba'.

努力が不足していたことを反省しています。

I am reflecting on the fact that my effort was insufficient.

Nominalizing the clause with 'koto'.

この地域では、雨が不足して作物が枯れた。

In this area, rain was insufficient and crops withered.

Describing environmental conditions.

現代人は慢性的に睡眠が不足していると言われている。

It is said that modern people are chronically lacking sleep.

Adverb 'manseiteki ni' (chronically).

その計画は、実現可能性の検討が不足している。

The plan lacks an examination of feasibility.

Complex noun phrase 'jitsugen kanousei no kentou'.

深刻な人手不足に直面している業界が多い。

Many industries are facing a serious labor shortage.

Using 'ni chokumen shite iru' (facing...).

コミュニケーションが不足すると、誤解が生じやすい。

When communication is insufficient, misunderstandings easily occur.

Using '~yasui' (prone to...).

証拠が不足しているため、起訴は見送られた。

Because evidence was insufficient, the indictment was deferred.

Legal/Formal register.

資源が不足する中で、どう生き残るかが課題だ。

In the midst of resources becoming insufficient, how to survive is the challenge.

Using 'naka de' (in the midst of).

配慮が不足していたことを深くお詫び申し上げます。

I deeply apologize for the lack of consideration.

Keigo (humble language) context.

この論文は、先行研究の調査が不足している。

This thesis lacks a survey of previous research.

Academic critique.

その政策は、弱者への視点が著しく不足している。

That policy remarkably lacks a perspective on the vulnerable.

Adverb 'ichijirushiku' (remarkably).

論理的整合性が不足しているため、説得力に欠ける。

Because it lacks logical consistency, it lacks persuasiveness.

Technical term 'ronriteki seigousei'.

供給が不足すれば、価格が高騰するのは自明の理だ。

It is self-evident that if supply becomes insufficient, prices will skyrocket.

Economic context; 'jimyou no ri' (self-evident truth).

彼は指導者としての資質が決定的に不足している。

He is decisively lacking the qualities of a leader.

Adverb 'ketteiteki ni' (decisively).

情報の非対称性により、市場の透明性が不足している。

Due to information asymmetry, market transparency is lacking.

Advanced economic theory terminology.

推敲が不足した原稿を世に出すわけにはいかない。

I cannot possibly release a manuscript that has been insufficiently polished.

Using 'wake ni wa ikanai' (cannot possibly).

この地域はインフラの整備が致命的に不足している。

The development of infrastructure in this region is fatally insufficient.

Adverb 'chimeiteki ni' (fatally/critically).

相手に対する敬意が不足していると言わざるを得ない。

I cannot help but say that respect for the other party is lacking.

Using 'to iwazaru wo enai' (cannot help but say).

文明の進歩に対し、倫理的議論が不足しているとの懸念がある。

There are concerns that ethical debate is lacking in response to the progress of civilization.

Complex societal critique.

その言説は、歴史的背景の考察が著しく不足していると言わざるを得ない。

It must be said that the discourse remarkably lacks consideration of the historical background.

Highly formal academic register.

自己批判の精神が不足すれば、組織は腐敗の一途をたどる。

If the spirit of self-criticism is lacking, the organization will continue to corrupt.

Using 'ippou wo tadoru' (to continue to...).

美的感性が不足している作品には、魂が宿らない。

A soul does not dwell in works that lack aesthetic sensibility.

Philosophical/Artistic register.

当事者意識が不足していることが、問題解決を遅らせている元凶だ。

The lack of a sense of ownership is the main culprit delaying problem resolution.

Using 'genkyou' (main culprit).

法整備の不足を突いた、巧妙な手口の犯罪が増えている。

Crimes using clever methods that exploit the lack of legal framework are increasing.

Using 'wo tsuita' (exploiting/hitting a weak point).

客観的データの不足により、その仮説は立証不可能なままである。

Due to the lack of objective data, that hypothesis remains unprovable.

Scientific/Formal register.

想像力が不足している人間ほど、他人に不寛容になりがちだ。

People who lack imagination tend to be more intolerant of others.

Psychological/Philosophical observation.

Common Collocations

睡眠が不足する

経験が不足する

予算が不足する

人手が不足する

説明が不足する

準備が不足する

運動が不足する

証拠が不足する

愛情が不足する

自信が不足する

Common Phrases

不足分を補う

— To make up for the lacking portion. Used when you need to fill a gap.

不足分を補うために、追加で注文した。

決定的な不足

— A decisive or critical lack. Used for major flaws.

それは決定的な不足だ。

慢性的不足

— Chronic shortage. Used for long-term problems.

この国は慢性的な水不足だ。

一歩不足

— One step short. Used when you almost reached a goal but failed slightly.

優勝にはあと一歩不足だった。

配慮不足

— Lack of consideration. Often used in apologies.

私の配慮不足でした。

言葉不足

— Lack of words/explanation. Used when you didn't explain well.

言葉不足で誤解を招いた。

人手不足の解消

— Resolving the labor shortage. A common political/business goal.

政府は人手不足の解消を目指している。

不足の事態

— An unforeseen situation (though 'fusoku' here uses different kanji 不測, they are often confused or discussed together).

不測の事態に備える。

栄養不足

— Malnutrition/Lack of nutrition. A medical term.

栄養不足で倒れた。

力不足

— Lack of ability/strength. Often used as a humble self-criticism.

力不足で申し訳ありません。

Often Confused With

不足する vs 足りない (tarinai)

Tarinai is for daily/casual use; fusoku is for objective/formal use.

不足する vs 欠ける (kakeru)

Kakeru is for a missing piece of a whole; fusoku is for a low total quantity.

不足する vs 不足 (noun)

The noun 'fusoku' can mean 'shortage' or 'unhappiness/complaint' (as in fusoku wo iu), but the verb 'fusoku suru' only means 'to lack'.

Idioms & Expressions

"帯に短し襷に長し"

— Too short for a belt, too long for a sash. Used when something is useless because it doesn't fit any purpose, often due to being 'fusoku' in one way and excess in another.

この布は帯に短し襷に長しで、使いにくい。

Literary/Idiom

"二の足を踏む"

— To hesitate (literally 'to step twice' with the foot kanji 足). While not directly 'fusoku', it involves the same kanji and indicates a 'lack' of courage.

新しい仕事に二の足を踏む。

Neutral

"足が出る"

— To go over budget (literally 'the feet stick out'). The opposite of 'fusoku' in quantity but indicates a 'fusoku' of original funds.

旅行で足が出てしまった。

Colloquial

"喉から手が出る"

— To want something desperately. Often used when one is 'fusoku' of something essential.

その時計は喉から手が出るほど欲しい。

Idiomatic

"爪の垢を煎じて飲む"

— To follow someone's example (to drink tea made from their fingernail dirt). Used when you 'lack' the talent of someone great.

彼の爪の垢を煎じて飲みたい。

Idiomatic

"無い袖は振れない"

— You can't wave sleeves you don't have. Used to say you can't give what you 'fusoku' (especially money).

貸してあげたいが、無い袖は振れない。

Proverb

"重箱の隅をつつく"

— To nitpick (poke the corners of a multi-tiered box). Often done when someone finds a 'fusoku' in a small detail.

彼は重箱の隅をつつくような批判をする。

Idiomatic

"焼け石に水"

— Water on a hot stone. Used when the help provided is so 'fusoku' it has no effect.

この寄付金では焼け石に水だ。

Proverb

"猫の手も借りたい"

— Willing to borrow even a cat's paw. Used during a severe 'hitode-fusoku' (labor shortage).

忙しくて猫の手も借りたい。

Idiomatic

"百も承知"

— Knowing perfectly well (100%). Often used when someone points out a 'fusoku' you already know about.

力不足は百も承知だ。

Idiomatic

Easily Confused

不足する vs 不測 (fusoku)

Identical pronunciation.

不測 (unforeseen) is used in 'fusoku no jitai' (unexpected situation). 不足 (insufficient) is about quantity.

不測の事態に備える vs 予算が不足する。

不足する vs 欠乏 (ketsubou)

Similar meaning.

Ketsubou is much more extreme, used for famine or total absence of nutrients.

食料が欠乏する。

不足する vs 欠如 (ketsujo)

Similar meaning.

Ketsujo is used for abstract traits (honesty, logic) that are missing.

道徳心の欠如。

不足する vs 枯渇 (kokatsu)

Means running out.

Kokatsu means 'to dry up' like a well or resources.

資源が枯渇する。

不足する vs 品切れ (shinagire)

Means not enough stock.

Shinagire is specifically 'sold out' in a shop.

その商品は品切れです。

Sentence Patterns

[Resource] が不足しています。

水が不足しています。

[Noun]不足です。

運動不足です。

[Resource] が不足しているため、[Result]。

予算が不足しているため、買えません。

[Resource] が不足すると、[Result]。

睡眠が不足すると、病気になります。

[Resource] の不足を補う。

経験の不足を補う。

[Resource] が著しく不足している。

人手が著しく不足している。

[Abstract Noun] が欠如・不足している。

論理性が不足している。

[Resource] の不足を露呈する。

準備の不足を露呈した。

Word Family

Nouns

不足 (Fusoku - shortage/insufficiency)

不足分 (Fusokubun - the lacking amount)

不足額 (Fusokugaku - the deficit amount)

Verbs

不足する (Fusoku suru - to lack)

足りる (Tariru - to be enough)

満たす (Mitasu - to satisfy/fill)

Adjectives

不足な (Fusoku na - insufficient/unhappy)

不十分な (Fujuubun na - inadequate)

欠乏 (Ketsubou)

欠如 (Ketsujo)

欠損 (Kesson)

赤字 (Akaji)

欠員 (Ketsuin)

How to Use It

frequency

Extremely high in news, medical, and business contexts.

Common Mistakes

経験を不足する → 経験が不足する
The thing lacking is the subject, not the object. Use 'ga'.
100円が不足しています → 100円足りません
Use 'tarinai' for specific small amounts of money in daily transactions.
野菜を不足している → 野菜が不足している
Again, the particle error. 'Fusoku suru' is intransitive.
不満足する → 不足する
Don't confuse 'insufficiency' with 'dissatisfaction' (fuman).
時間が不足だ → 時間が不足している
While 'fusoku' is a noun, it's more natural to use the verb form 'shite iru' to describe a state.

Tips

Subject Marker

Always use 'ga' with the resource that is lacking. 'Mizu ga fusoku suru'.

Medical Use

Use it for sleep, exercise, and vitamins to sound like you are taking your health seriously.

Business Tone

Use 'fusoku' in reports and emails to maintain a professional, objective tone.

Compound Nouns

Learn it as part of compounds like 'suimin-fusoku' for easier recall.

Fusoku vs Tarinai

Think of 'fusoku' as a 'shortage' (macro) and 'tarinai' as 'not enough' (micro).

The 'i' drop

In casual talk, people say 'fusoku shiteru' instead of 'shite iru'.

Apologies

'Watashi no chikara-fusoku' is a classic humble way to apologize for a failure.

Kanji Meaning

Remember: Not (不) + Enough (足) = Lack.

News Keywords

'Hitode-fusoku' (labor shortage) is one of the most common words on Japanese TV.

Politeness

Using 'fusoku' can soften a criticism by making it sound like a resource issue rather than a personal failing.

Memorize It

Mnemonic

Think of a 'FOOt' (足) that is 'NOT' (不) there. If you don't have a foot, you 'LACK' the ability to stand properly. 'FU-SOKU' = 'No-Foot' = 'Lack'.

Visual Association

Imagine a bucket of water with a line marked 'Required'. The water level is below the line. A big red 'X' (不) is over the 'Foot' (足) of the bucket.

Word Web

Water Sleep Money Time Experience Labor Exercise Budget

Challenge

Try to find three things in your life right now that are 'fusoku shite iru' (e.g., coffee, free time, battery life) and say them aloud in Japanese.

Word Origin

Sino-Japanese (Kango). The word 'Fusoku' entered Japanese via Classical Chinese. 'Fu' (不) is a negative prefix, and 'Soku' (足) means foot or to be sufficient. The 'foot' meaning comes from the idea of reaching a destination or standing firmly.

Original meaning: Not reaching the standard; not being enough to stand on.

Japonic (Sino-Japanese vocabulary).

Cultural Context

Be careful when using 'fusoku' to describe a person's qualities (like 'intelligence lacks'), as it can sound very cold and clinical compared to 'tarinai'.

English speakers often use 'lack' as a transitive verb ('I lack money'). In Japanese, 'money' is the subject ('Money lacks'). This shift in perspective is key.

NHK News 'Hitode-fusoku' specials Health posters in Japanese clinics Business reports on 'Yosan-fusoku'

Practice in Real Life

Real-World Contexts

Health/Doctor

睡眠不足です
ビタミンが不足しています
運動不足を解消する
栄養不足の症状

Business/Meeting

予算が不足している
人手不足が深刻だ
説明が不足していた
資料の不足

News/Economy

電力不足の恐れ
米不足が起きる
資源が不足する
資金不足に陥る

Daily Life

時間が不足している
言葉不足でごめん
準備不足だった
野菜不足を感じる

Education

努力が不足している
練習不足だ
知識が不足する
根拠が不足している

Conversation Starters

"最近、何か不足していると感じることはありますか？ (Is there anything you feel you're lacking lately?)"

"仕事で人手不足を感じることはありますか？ (Do you feel a labor shortage at work?)"

"睡眠不足の時はどうやって対処していますか？ (How do you deal with it when you're lacking sleep?)"

"野菜不足を解消するために何を食べていますか？ (What do you eat to fix a lack of vegetables?)"

"このプロジェクト、予算が不足する心配はありませんか？ (Are you worried about the budget being insufficient for this project?)"

Journal Prompts

今日の自分に不足していたものは何ですか？ (What was lacking in yourself today?)

今の日本（または自分の国）で最も不足している資源は何だと思いますか？ (What resource do you think is most lacking in Japan/your country now?)

経験が不足していることで困った経験を書いてください。 (Write about an experience where you struggled due to a lack of experience.)

運動不足を解消するために、来週は何をしますか？ (What will you do next week to fix your lack of exercise?)

「言葉不足」で誰かと喧嘩したことはありますか？ (Have you ever fought with someone due to a 'lack of words'?)

Frequently Asked Questions

10 questions

Yes, but usually in terms of 'manpower' (hitode-fusoku) or 'number of members' (ninzuu-fusoku). If you mean a specific person is missing, use 'kakeru'.

'Tarinai' is an adjective-like verb used casually (e.g., 'not enough salt'). 'Fusoku shite iru' is a formal Suru-verb used for resources and health (e.g., 'lack of sleep').

It is always '経験が不足する'. The thing that is lacking is the subject, not the object.

Yes, as a noun in the phrase '不足を言う' (to complain/express dissatisfaction). However, the verb '不足する' does not carry this meaning.

Casually: 'Okane ga tarinai'. Formally: 'Genkin ga fusoku shite iru'. Business slang: 'Shinki ga shōto shite iru'.

Yes, it means 'slightly lacking'. People often say 'yasai-fusoku-gimi' (tending to lack vegetables).

Yes, 'jikan-fusoku' is common, but 'jikan ga tarinai' is more common in daily speech.

It refers to the specific amount that is missing. 'Fusokubun wo harau' means 'to pay the remaining balance'.

Very much so. It is used for 'oxygen deficiency' (sanso-fusoku) or 'nutrient deficiency'.

It is a standard way to say 'the explanation was not enough'. It is less rude than 'You didn't explain well'.