Grammar Rule in 30 Seconds
Use 'It' as a placeholder subject when the real subject is a long clause or when talking about weather, time, or distance.
- Use 'It' for weather, time, and distance: 'It is raining.'
- Use 'It' to move long infinitive or 'that' clauses to the end: 'It is vital to study.'
- Use 'It' for opinions about situations: 'It's a shame you can't come.'
Overview
To learn English is difficult. とすると、少し古風で堅苦しい響きになります。より自然な英語では It is difficult to learn English. と表現します。この It は何を指しているわけでもありません。ただ、文の構造を整えるためにそこに存在しているのです。この「情報の重さを後ろに回す（End-weight principle）」という英語特有の性質を理解することは、ネイティブのような自然なリズムを身につけるための必須条件です。この解説を通じて、なぜ英語がこのような構造を好むのか、その論理的な背景を深く理解していきましょう。It を主語の位置に配置し、重い内容を文末に送るというテクニックです。これを言語学では「外置（Extraposition）」と呼びます。It を先に置いて、動詞を早期に出現させることで、聞き手が文の骨格を素早く把握できるようにしているのです。It is essential that you attend the meeting. という文では、まず It is essential と断言することで、聞き手に「重要事項である」というサインを先に送り、その後に具体的な内容を提示しています。これは、日本語の「〜ということが重要です」という構造とは異なり、結論や評価を先に伝える英語の論理的な思考プロセスを反映しています。It is important to study hard. |It is likely that he will win. |It is easy for me to run. |I find it hard to believe. |for A を入れる位置や、that 節の中身を正しく組み立てる練習は、ライティングの精度を大きく左右します。- 1意見や評価を述べる時: 自分の主観的な判断を述べる際、
It is + 形容詞の形で文を始めると非常にスマートです。例えば、会議で「このプロジェクトを延期するのは妥当だと思います」と伝えたい時、It is reasonable to postpone this project.と言えば、客観的な説得力が増します。 - 2ルールや必要性を説明する時:
It is necessary to...やIt is mandatory to...は、仕事の指示やルール説明で必須のフレーズです。これは「〜することが求められている」というニュアンスを強調します。 - 3感情を表現する時:
It is exciting to...やIt is disappointing that...のように、出来事に対する自分の感情を後から付け加えることで、感情の動きを強調する効果があります。
- 1主語の脱落 (Pro-drop): 日本語は主語を省略する言語です。そのため、
Is difficult to understand.と言ってしまうことがよくあります。英語ではItを必ず置かなければなりません。 - 2Referential 'it' との混同:
Itが何かを指していると勘違いし、文脈がないのに「それは〜です」と訳そうとするケースです。ダミーのitは「それ」とは訳しません。文全体を指すのではなく、後ろの節を導くための「信号」だと考えてください。 - 3
forの位置間違い:It is hard to finish for me.と言ってしまうミスです。正しくはIt is hard for me to finish.です。for Aはto不定詞の動作主（誰がやるか）を示すため、必ずtoの直前に置く必要があります。
It is fun to travel. |I bought a book. It is fun. |It was John that I saw. |It は「〜なのはまさに…だ」と訳しますが、形式主語の It は訳さない、という違いを意識しましょう。この違いを理解できれば、あなたの英語は一段と洗練されます。努力を続けて、ぜひ使いこなしてください！Common Dummy 'It' Structures
| Structure | Function | Example |
|---|---|---|
|
It + be + Adjective + to-infinitive
|
Giving an opinion on an action
|
It is hard to say goodbye.
|
|
It + be + Adjective + that-clause
|
Reporting a fact or belief
|
It is clear that he is lying.
|
|
It + take + Time + to-infinitive
|
Expressing duration
|
It takes an hour to cook.
|
|
It + seem/appear + that-clause
|
Expressing an impression
|
It seems that they are late.
|
|
It + be + Noun + that-clause
|
Emphasizing a specific part (Cleft)
|
It was John who called.
|
|
It + be + Weather/Time/Distance
|
Describing the environment
|
It is windy today.
|
Contractions with Dummy 'It'
| Full Form | Contraction | Usage |
|---|---|---|
|
It is
|
It's
|
Very common in speech/informal writing
|
|
It was
|
N/A
|
Rarely contracted in standard English
|
|
It will
|
It'll
|
Common in spoken English
|
|
It has
|
It's
|
Used in present perfect (e.g., It's been a long day)
|
Meanings
The dummy 'it' is a pronoun that has no semantic meaning of its own but serves as a grammatical subject to satisfy the English requirement that every sentence must have a subject.
Ambient/Environmental
Used to describe weather, time, temperature, and distance where no specific agent is performing an action.
“It is nearly midnight.”
“It's freezing in this room.”
Extraposition
Used to shift a heavy subject (like an infinitive phrase or a 'that' clause) to the end of the sentence for better flow.
“It is unlikely that they will arrive on time.”
“It was a mistake to trust him with the secret.”
Identifying People
Used to identify a person when their identity is not yet established or when speaking on the phone/intercom.
“It's me, Sarah!”
“Who is it at the door?”
Reference Table
| タイプ | 構造 | 例文 | 目的 |
|---|---|---|---|
|
意見・判断
|
It + is + adjective + to-infinitive
|
It's wonderful to meet you.
|
個人的な感情を一般的に表現する
|
|
事実・真実
|
It + is + adjective + that-clause
|
It is true that honesty is best.
|
客観的な真実を述べる
|
|
必要性・義務
|
It + is + necessary/important + to-infinitive
|
It is essential to stay hydrated.
|
すべきことを示す
|
|
難易度
|
It + is + easy/hard + to-infinitive
|
It's easy to get lost here.
|
挑戦のレベルを説明する
|
|
観察
|
It + seems/appears + adjective + to-infinitive
|
It seems difficult to explain.
|
印象や観察結果を共有する
|
|
フォーマルな声明
|
It + is + believed/said + that-clause
|
It is widely believed that practice helps.
|
一般的な合意事項を報告する
|
フォーマル度スペクトル
It is anticipated that the situation will prove challenging. (Discussing a problem)
It is going to be a difficult situation. (Discussing a problem)
It's gonna be tough. (Discussing a problem)
It's gonna be a beast. (Discussing a problem)
形式主語 'It' の仕組み
基本構造
- It + 動詞 (be動詞) It is / It was
- + 形容詞/名詞句 It's important / It's a shame
- + 真の主語 (to不定詞) to finish the report
- + 真の主語 (that節) that she passed the exam
主な用途
- 意見・判断 It's great to see you.
- 事実・真実 It is known that…
- 必要性・義務 It's crucial to prepare.
- 難易度 It's hard to decide.
なぜ使うのか？
- スムーズな流れ 長い主語による違和感を避ける。
- 強調 形容詞や名詞句を際立たせる。
- 明快さ 聞き手が理解しやすくなる。
- 自然さ ネイティブらしい響きになる。
Dummy 'It' vs. 代名詞の 'It'
Dummy 'It' を使うべき？
文に主語が必要ですか？
本当の「主語」は不定詞句やthat節ですか？
Dummy 'It' とよく使われる語句
よく使われる形容詞
- • important
- • easy
- • difficult
- • clear
- • possible
- • true
- • great
- • necessary
- • good
- • challenging
よく使われる動詞
- • is
- • was
- • seems
- • appears
- • proves
- • makes
使われる場面
- • 意見
- • 事実
- • 必要性
- • 難易度
- • 時間
- • 天候
- • 観察
- • 判断
レベル別の例文
It is 9:00 AM.
Son las 9:00 AM.
It is cold today.
Hace frío hoy.
It is a big house.
Es una casa grande.
Is it Monday?
¿Es lunes?
It is nice to see you.
Es un gusto verte.
It's a long way to the city.
Es un largo camino a la ciudad.
It was dark in the room.
Estaba oscuro en la habitación.
It is easy to cook pasta.
Es fácil cocinar pasta.
It is important to finish your homework.
Es importante terminar tu tarea.
It takes 20 minutes to walk there.
Toma 20 minutos caminar allá.
It doesn't matter if you are late.
No importa si llegas tarde.
It seems that she is busy.
Parece que ella está ocupada.
It is often argued that social media is addictive.
A menudo se argumenta que las redes sociales son adictivas.
It occurred to me that I had forgotten my keys.
Se me ocurrió que había olvidado mis llaves.
It is vital that we reach a consensus.
Es vital que lleguemos a un consenso.
It makes no difference what they think.
No hace ninguna diferencia lo que ellos piensen.
It was with great reluctance that he accepted the offer.
Fue con gran renuencia que aceptó la oferta.
It is incumbent upon us to protect the environment.
Nos incumbe a nosotros proteger el medio ambiente.
It remains to be seen whether the plan will work.
Queda por ver si el plan funcionará.
It is no exaggeration to say she is a genius.
No es exagerado decir que ella es una genio.
It is high time the government addressed this issue.
Ya es hora de que el gobierno aborde este problema.
It behooves the board to reconsider their stance.
Le corresponde a la junta reconsiderar su postura.
It is not so much that he failed, but that he didn't try.
No es tanto que fallara, sino que no lo intentó.
It is a truth universally acknowledged that a single man must be in want of a wife.
Es una verdad universalmente reconocida que un hombre soltero debe necesitar una esposa.
間違えやすい
Learners use 'This' to start general sentences. 'This' refers to a specific object you can point to; 'It' is for general situations.
Both are placeholders, but 'There' is for existence and 'It' is for identity/state.
Using 'It' for people. While 'It' identifies someone ('It's me'), you must switch to 'He/She' once the person is known.
よくある間違い
Is raining.
It is raining.
Today is Monday.
It is Monday today.
Is 5 o'clock.
It is 5 o'clock.
Is hot.
It is hot.
Is important to study.
It is important to study.
This is cold today.
It is cold today.
Is far to the beach.
It is far to the beach.
To learn English is easy.
It is easy to learn English.
There is important to go.
It is important to go.
Is seems that he is late.
It seems that he is late.
It is likely for him to win.
It is likely that he will win.
文型パターン
It is ___ to ___.
It takes ___ to ___.
It is ___ that ___.
It was ___ who ___.
Real World Usage
It's fine, don't worry about it!
It is my belief that my skills align with this role.
It is currently 72 degrees and sunny.
It is widely recognized that further research is needed.
It takes about 10 minutes to reach the station.
It's the way he looks at her for me! 😍
まずは結論、詳細は後で
Itを絶対に落とさないで！
形容詞のバリエーションを増やす
より自然な響きを目指して
Smart Tips
Flip it! Use 'It is [adjective] to [verb]' to sound 10x more natural.
Ask: Am I saying 'Something exists' or 'Something is like this'? If it's 'like this', use 'It'.
Use 'It is argued that' instead of 'I think' to sound more professional and objective.
Always use 'It's [Name]'. Never say 'I am [Name]'.
発音
The 'It's' Reduction
In fast speech, 'It is' or 'It's' often sounds like a very short /ts/ or /ɪts/.
Linking 'It' to Verbs
When 'it' is followed by a verb starting with a vowel, they link together.
Extraposition Stress
It is VITAL to GO.
Stress falls on the adjective and the main verb of the extraposed clause, not on 'it'.
暗記しよう
記憶術
Remember: 'It' is the 'Invisible Tenant'—he doesn't own the house (the meaning), but he has to be there for the house to stand!
視覚的連想
Imagine a small robot named 'IT' holding up a heavy sign that says 'TO LEARN ENGLISH'. The robot is small and doesn't do much, but without him, the heavy sign would fall on the floor.
Rhyme
When the subject is a clause or the weather is a bit... start your sentence with a dummy 'it'!
Story
Once there was a sentence that wanted to talk about the rain, but it had no subject. It tried 'Is raining,' but the Grammar Police stopped it. Then, a little word named 'It' volunteered to stand at the front. 'I don't mean anything,' said It, 'but I'll keep the seat warm for you.'
Word Web
チャレンジ
Look out the window and describe the weather, the time, and one opinion about your day using only 'It' as the subject. (e.g., 'It is cloudy. It is 2 PM. It is nice to be home.')
文化メモ
British people famously use the dummy 'it' to talk about the weather as a social icebreaker. 'It's a bit nippy out, isn't it?' is a classic conversation starter.
In Western academic culture, using 'It is argued' or 'It is believed' is a way to show humility and objectivity, avoiding the 'I' which can seem too aggressive or biased.
In casual American English, 'It' is often dropped in very informal speech, though it remains grammatically required in writing.
Derived from the Old English 'hit', which functioned as a neuter third-person pronoun.
会話のきっかけ
It's a beautiful day, isn't it?
It's important to have a work-life balance. Do you agree?
It seems that technology is changing too fast. What do you think?
It is often said that travel broadens the mind. Has it been true for you?
日記のテーマ
よくある間違い
Test Yourself
___ is essential to proofread your essays before submission.
Find and fix the mistake:
To get a good job is challenging in today's market.
英語に訳しましょう： 'Es importante recordar tus sueños.' (夢を覚えていることは重要です)
Answer starts with: ["I...
Arrange the words in the correct order:
All words placed
Click words above to build the sentence
Score: /4
練習問題
8 exercises___ is very cold in this room.
Find and fix the mistake:
Is important to be on time.
Which sentence sounds best to a native speaker?
takes / it / to / an / hour / cook / dinner
Translate the Spanish phrase into English.
1. It's 5:00. 2. It's raining. 3. It's far.
Complete the sentence using a that-clause.
Identify the dummy 'it'.
Score: /8
Practice Bank
11 exercises___ is vital that you understand the terms and conditions.
Seems difficult to concentrate with all this noise.
最も自然な文を選んでください：
英語に訳しましょう： '残念ながら出席できません。'
単語を並べ替えてください：
文の断片を組み合わせてください：
___ is common knowledge that exercise is beneficial for health.
That we missed the deadline was regrettable.
正しい文はどれですか？
英語に訳しましょう： '彼にとって真実を受け入れるのは困難でした。'
単語を並べ替えてください：
Score: /11
よくある質問 (8)
No. We always use `it` for weather. Saying `This is raining` sounds like you are pointing at a specific puddle rather than the weather in general.
English is a 'non-pro-drop' language, meaning every sentence needs a subject to be grammatically complete. `It` is a placeholder that satisfies this rule.
In modern English, `It is me` is the standard and most natural form. `It is I` is extremely formal and rarely used today.
Extraposition is moving a long subject to the end of the sentence and putting `it` at the start. For example: `It is hard to believe he left.`
Yes! You can use it with verbs like `seem`, `appear`, `happen`, `matter`, and `take`. Example: `It doesn't matter.`
Not always. `It's` can be `It is` or `It has` (in the present perfect). Example: `It's been a long time` means `It has been a long time.`
In very informal texting, people sometimes drop the 'it', but it's better to keep it to avoid sounding like a non-native speaker.
It's a sentence where you use `It is... that` to emphasize one part. Example: `It was my brother who ate the cake` (not my sister).
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
Null subject
Spanish omits the subject entirely; English requires 'It'.
Il / Ce
French distinguishes between 'Il' and 'Ce' where English mostly uses 'It'.
Es
The usage is almost identical.
Zero pronoun
Japanese has no equivalent to a dummy placeholder.
Null subject / Hidden pronoun
Arabic uses verb conjugation to imply the subject instead of a placeholder word.
Topic-comment structure
Chinese focuses on the event rather than the grammatical subject.
Learning Path
Prerequisites
関連動画
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12:54 Inside Out 1 & 2 | Full Story Recap | Ending Scenes & Final Battles | Joy vs Sadness & Anxiety Fight
【It is...to/that...】形式主語のItをマスターしよう！
Hapa 英会話
It is... to... 構文の本当の意味と使い方
Atsueigo
【形式主語It】It is ~ to ... の使い方を徹底解説！
Hapa 英会話
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