Grammar Rule in 30 Seconds
Use object pronouns (him/her/them) after 'let', but subject pronouns (he/she/they) when they are the main subject of a verb like 'know'.
- Always use 'him', 'her', or 'them' after 'let' (e.g., 'Let him speak').
- Use 'he', 'she', or 'they' before 'know' (e.g., 'He knows the answer').
- Never say 'Let he' or 'Him knows' in standard modern English.
Overview
let という動詞の後に he を使うべきか him を使うべきか、あるいは I なのか me なのかという問題は、中級者（B1レベル）の方でもうっかり間違えてしまうことが少なくありません。今回のレッスンでは、この「Let-he vs. I-know」というテーマを通じて、英語の格（Case）のルールと、let に代表される「使役動詞」の構造を深く掘り下げていきましょう。let という単語は、日常会話からビジネスシーンまで頻繁に登場します。Let me check.（確認させてください）や Let's go.（行きましょう）といった表現は耳に馴染みがあると思いますが、その裏側にある文法ルールを正しく理解することで、応用力が飛躍的に向上します。この解説を読み終える頃には、自信を持って適切な代名詞を選べるようになっているはずです。I, you, he, she, it, we, they |me, you, him, her, it, us, them |let という動詞の性質です。let は「他動詞」であり、その直後に「誰に（何に）対してその動作を許すのか」という目的語を必要とします。英語のルールでは、動詞の目的語になるポジションには必ず目的格を置かなければなりません。I know him.（私は彼を知っている）という文を見てみましょう。ここでは I が主語で、him が目的語です。これを *I know he. と言うことはありませんよね？ これと同じ理屈が let にも適用されます。Let は命令文の形で使われることが多いため、主語の You が省略されていますが、構造としては (You) let him go. となり、let のすぐ後ろは目的語のポジションなのです。he を使いたくなってしまうかもしれません。しかし、英語では「許可を与える対象」をまず目的語として提示し、その後にその人が何をするのか（動詞の原形）を続けるという構造をとります。この「動詞 + 目的語 + 動詞の原形」という形は、英語特有の非常に論理的な組み立て方です。let を使った文章の組み立て方は、非常にシンプルで一貫性があります。以下のパターンを公式として覚えてしまいましょう。- 1主語 (Subject): 許可を与える人や状況です。命令文の場合は省略されます。
- 2let: 「〜させる」「〜させてやる」という意味の動詞です。主語が三人称単数の場合は
letsになり、過去形もletのままです。 - 3目的格代名詞 (Object Pronoun): ここが今回のポイントです。
me,him,her,us,themを使います。 - 4動詞の原形 (Base Verb): ここで注意が必要なのは、
toを付けない「裸不定詞」を使うという点です。*let him to goとは言いません。
My boss let me finish work early.（上司は私を早く退社させてくれた）Please let him explain the situation.（彼に状況を説明させてあげてください）We won't let them enter the building.（彼らを建物内には入れさせない）
Let's という表現も、実はこのパターンの一部です。Let's は Let us の短縮形です。つまり、us（私たちを）という目的格が隠れているのです。Let's eat. は直訳すれば「私たちに食べることを許して（＝食べましょう）」という意味になります。このように、一見特別な熟語に見える表現も、実はしっかりとした文法ルールに基づいています。let + 目的格の形は、主に以下の5つのシチュエーションで使用されます。それぞれの場面で、なぜ目的格が使われるのかを意識してみてください。- 1許可を与える (Granting Permission):
I'll let you use my laptop.（私のノートパソコンを使わせてあげよう）The teacher let the students leave early.（先生は生徒たちが早く帰るのを許可した）
- 1提案をする (Making Suggestions):
Let's を使った表現です。自分を含めたグループに対して行動を促します。Let's discuss this over lunch.（ランチを食べながらこれについて話し合いましょう）Let's not worry about it now.（今はそのことを心配するのはやめましょう）
- 1丁寧に許可を求める・申し出る (Asking/Offering Politely):
Let me... という形で、自分が何かをすることを相手に伝えたり、許可を求めたりします。ビジネスシーンで非常に重宝する表現です。Let me introduce myself.（自己紹介をさせてください）Let me know if you need any help.（助けが必要なら知らせてください）
- 1状況をそのままにする (Allowing a State):
Let the water boil for five minutes.（お湯を5分間沸騰させておいてください）Don't let the opportunity slip away.（チャンスを逃さないようにしなさい）
- 1指示や命令 (Giving Instructions):
Let each candidate prepare a short speech.（各候補者に短いスピーチを準備させてください）
- 間違い:
*My father lets I drive his car. - 正しい:
My father lets me drive his car. - 解説: 日本語では「父は私が車を運転するのを許す」となるため、主格の
Iを使いたくなります。しかし、英語のletは「私（me）を」許可の対象として捉えるため、必ず目的格にする必要があります。動詞の直後は「目的語の席」であることを忘れないでください。
to を入れてしまう- 間違い:
*Please let him to go home. - 正しい:
Please let him go home. - 解説:
allowという動詞（allow him to go）と混同してしまいがちです。letは使役動詞の仲間であり、後ろにtoを取らないという強力なルールがあります。これは「使役のletはtoなし」とリズムで覚えてしまいましょう。
Let's を「さあ」という掛け声だと思い込む- 間違い:
*Let's you and I go. - 正しい:
Let's go, just the two of us. - 解説:
Let'sの中にすでにus（私たち）が含まれていることを忘れ、さらにyou and Iなどの主語を付け足してしまうミスです。Let'sはそれ自体で「私たち（目的格）に〜させて」という完結した構造を持っています。
let と似た意味を持つ動詞に allow や make があります。これらは使い分けが難しいため、表で比較してみましょう。let + 目的語 + 原形 | Let him stay. |allow + 目的語 + to 不定詞 | Allow him to stay. |make + 目的語 + 原形 | Make him stay. |have + 目的語 + 原形 | Have him stay. |letとallowは意味は似ていますが、toを使うかどうかが決定的な違いです。ビジネスメールなどではallowやpermitが好まれますが、日常会話ではletが圧倒的に自然です。makeは本人の意思に関係なく強制するニュアンスがあるため、let（本人がやりたいことを許す）とは正反対のエネルギーを持っています。代名詞の形（目的格）はどちらも同じです。
Let's の後に me を入れることはできますか？Let's は Let us の略なので、すでに目的語が含まれています。自分のことを言いたい場合は Let me... を使い、自分たちを含めた提案をしたい場合は Let's... を使い分けましょう。He let me go.（彼は私を行かせてくれた）のように、過去の話でも常に目的格を使います。let の後に名前が来る場合はどうなりますか？Let Tanaka-san handle this.（田中さんにこれを任せましょう）。代名詞に置き換える時だけ、him や her に変える必要があります。Let he go はそんなに不自然に聞こえるのですか？he, I, she）が来るのは、語順のルールを根本から破壊しているように感じられるからです。日本語で「彼をは行く」と言っているような違和感に近いかもしれません。正しい格を使うことは、英語の「リズム」を守ることでもあるのです。Pronoun Case Selection
| Person | Subject (with Know) | Object (with Let) | Example with Let | Example with Know |
|---|---|---|---|---|
|
1st Sing.
|
I
|
me
|
Let me go.
|
I know him.
|
|
2nd Sing.
|
you
|
you
|
Let you be.
|
You know me.
|
|
3rd Sing. (M)
|
he
|
him
|
Let him stay.
|
He knows it.
|
|
3rd Sing. (F)
|
she
|
her
|
Let her speak.
|
She knows us.
|
|
1st Plur.
|
we
|
us
|
Let us (Let's) eat.
|
We know them.
|
|
3rd Plur.
|
they
|
them
|
Let them try.
|
They know why.
|
Common Contractions
| Full Form | Contraction | Usage Note |
|---|---|---|
|
Let us
|
Let's
|
Used for suggestions (Let's go!)
|
|
He knows
|
He's known
|
Present perfect (He has known)
|
|
Do not let
|
Don't let
|
Negative imperative
|
|
Does not know
|
Doesn't know
|
Negative declarative
|
Meanings
This rule distinguishes between the causative/imperative use of 'let' (which requires an object pronoun) and the declarative use of 'know' (which requires a subject pronoun).
Permission/Causative
Using 'let' to allow someone to do something or to suggest an action.
“Let her finish her sentence.”
“Don't let them enter the room yet.”
Assertion/Knowledge
Using 'know' to state that a subject possesses information.
“He knows exactly what happened.”
“They know how to fix the car.”
Idiomatic Suggestions
Using 'Let's' as a contraction for 'Let us' to make a group proposal.
“Let's go to the beach!”
“Let's not talk about that right now.”
Reference Table
| Form | Structure | Example |
|---|---|---|
|
Affirmative Let
|
Let + Object + Verb
|
Let him enter.
|
|
Affirmative Know
|
Subject + Know(s)
|
He knows the way.
|
|
Negative Let
|
Don't let + Object + Verb
|
Don't let her fall.
|
|
Negative Know
|
Subject + doesn't know
|
She doesn't know.
|
|
Question Let
|
Will you let + Object + Verb?
|
Will you let them stay?
|
|
Question Know
|
Does + Subject + know?
|
Does he know you?
|
|
Suggestion
|
Let's + Verb
|
Let's start now.
|
フォーマル度スペクトル
Please permit him to enter the premises. (Security/Home)
Let him come in. (Security/Home)
Let him in. (Security/Home)
Let 'im in. (Security/Home)
The Pronoun Split
After 'Let'
- Him Object
- Her Object
- Them Object
Before 'Know'
- He Subject
- She Subject
- They Subject
Let vs. Know
Which Pronoun Do I Use?
Is the word after 'Let'?
Is the word the subject of 'Know'?
レベル別の例文
Let's go to the park.
Let's go to the park.
I know your name.
I know your name.
Let him play.
Let him play.
He knows me.
He knows me.
Don't let her cry.
Don't let her cry.
She knows the answer.
She knows the answer.
Let them come inside.
Let them come inside.
They know we are here.
They know we are here.
Let him decide; he knows what he wants.
Let him decide; he knows what he wants.
If you let her help, she will feel better.
If you let her help, she will feel better.
We know they are busy, so let's not bother them.
We know they are busy, so let's not bother them.
Let us know if you need anything.
Let us know if you need anything.
Rather than forcing the issue, let him come to his own conclusion.
Rather than forcing the issue, let him come to his own conclusion.
She knows full well that we can't let them stay past midnight.
She knows full well that we can't let them stay past midnight.
Let it be known that he knows nothing of our plans.
Let it be known that he knows nothing of our plans.
Don't let their opinions discourage you; you know your worth.
Don't let their opinions discourage you; you know your worth.
Let him who is without sin cast the first stone, for he knows the weight of guilt.
Let him who is without sin cast the first stone, for he knows the weight of guilt.
Should they refuse to cooperate, let them face the consequences.
Should they refuse to cooperate, let them face the consequences.
He knows the intricacies of the law, so let him handle the negotiations.
He knows the intricacies of the law, so let him handle the negotiations.
Let us not pretend that she knows more than she actually does.
Let us not pretend that she knows more than she actually does.
The director was adamant: let them flounder if they must, provided they know the risks.
The director was adamant: let them flounder if they must, provided they know the risks.
Let there be no doubt that he knows exactly where the bodies are buried.
Let there be no doubt that he knows exactly where the bodies are buried.
To let him believe otherwise would be a disservice, as he knows the truth deep down.
To let him believe otherwise would be a disservice, as he knows the truth deep down.
Let us delve into the archives; she knows where the key is hidden.
Let us delve into the archives; she knows where the key is hidden.
間違えやすい
Learners often use 'leave' when they mean 'allow' (e.g., 'Leave me go').
Both are causative, but 'let' is about permission while 'make' is about force.
They mean the same thing but have different grammar.
よくある間違い
Let he go.
Let him go.
Him knows.
He knows.
Let's we go.
Let's go.
Let me to help.
Let me help.
Don't let they see.
Don't let them see.
She know him.
She knows him.
Let her to speak.
Let her speak.
Let him who knows tell us.
Let him who knows tell us.
I let him to know the truth.
I let him know the truth.
He let her knows.
He let her know.
Let he who is without sin...
Let him who is without sin...
文型パターン
Let ___ (object) ___ (verb).
___ (subject) knows that ___.
Don't let ___ (object) ___ (verb) until ___.
If you let ___ (object) ___ (verb), ___ (subject) will know ___.
Real World Usage
Let me know when u r here.
I know I can contribute to this team if you let me show my skills.
Let them hate, she knows she's iconic.
Let us through, we know our flight is boarding.
Let him leave it at the door, he knows the code.
Let's get the pizza, everyone knows it's the best.
The Finger Test
No 'To' Allowed
Let's vs. Let us
Polite Suggestions
Smart Tips
Stop! Think of the word 'him'. If you can't say 'Let him', you shouldn't say 'Let he'.
Use 'Let me know' instead of 'Tell me'. It sounds more polite and professional.
Remember it's a group activity. If you are alone, use 'Let me'.
The pronoun between them must be an object, but the pronoun before 'know' in a new clause must be a subject.
発音
Let's Contraction
The 's' in 'Let's' is pronounced as /s/, not /z/.
Let him Reduction
In fast speech, the 'h' in 'him' is often dropped.
Imperative Let
Let him GO! ↘
A strong command or insistence.
暗記しよう
記憶術
Let the OBJECT in; the SUBJECT KNOWS the way.
視覚的連想
Imagine a gatekeeper named 'Let' who only allows people carrying 'Object' bags (him, her, them) to pass. Next to him is a wise man named 'Know' who only talks to 'Subject' kings (he, she, they).
Rhyme
After Let, use Him or Her. Before Know, use He or She, for sure!
Story
A king (He) knows where the treasure is. He tells the guard, 'Let him (the servant) go find it.' The king is the subject who knows, but the servant is the object being let go.
Word Web
チャレンジ
Write 5 sentences about your family using 'Let' and 'Know' correctly (e.g., 'I let him cook because he knows the recipe').
文化メモ
Using 'Let's' is the most common way to make a suggestion without sounding bossy. It implies equality.
You might hear 'Let us' used more formally in religious contexts, whereas 'Let's' is universal.
The phrase 'Let him be' is a common way to say 'Leave him alone'.
The word 'let' comes from the Old English 'lætan', meaning to leave, allow, or bequeath. 'Know' comes from 'cnawan', meaning to perceive or recognize.
会話のきっかけ
Let's decide on a movie. Do you know any good ones?
If you could let anyone in the world lead your country, who would it be?
Let's talk about your future. What do you know for sure?
Do you let your friends borrow your car? Why or why not?
日記のテーマ
よくある間違い
Test Yourself
Let ___ finish his work; ___ knows what he is doing.
Which sentence is correct?
Find and fix the mistake:
She let he stay because she knows him.
He is allowed to leave.
A: Should I tell him? B: No, don't let ___ know yet.
Select the correct group.
You should use 'to' after the word 'let'.
Match each item on the left with its pair on the right:
Score: /8
練習問題
8 exercisesLet ___ finish his work; ___ knows what he is doing.
Which sentence is correct?
Find and fix the mistake:
She let he stay because she knows him.
He is allowed to leave.
A: Should I tell him? B: No, don't let ___ know yet.
Select the correct group.
You should use 'to' after the word 'let'.
He -> ?, They -> ?, We -> ?
Score: /8
Practice Bank
14 exercisesCould you let ___ borrow your pen for a second?
Don't let ___ boss you around like that!
Her parents let she and her brother use the car.
Choose the correct sentence:
Translate into English: 'Déjame pensar un momento.'
Arrange these words into a sentence:
Match the subjects with their object forms:
Just let ___ know what you decide.
Let he and I figure it out ourselves.
Arrange these words into a sentence:
Choose the correct sentence:
Translate into English: 'El policía le dejó ir con una advertencia.'
Match the sentence parts:
Arrange these words into a sentence:
Score: /14
よくある質問 (8)
'Let's' is a contraction of `Let us`. In modern English, we use the contraction for suggestions and the full form only for very formal permission.
This is a famous biblical quote. While it uses `he` (subject), it is considered archaic. In modern conversation, you should always use `him`.
It can be both! Context matters. If a boss says it, it's a command. If a friend says it about a bad boyfriend, it's a suggestion.
`Let him` is followed by a base verb (`Let him go`). `Allow him` is followed by 'to' (`Allow him to go`).
This is actually grammatically incorrect (it should be 'you and me'), but it is a common mistake even among native speakers.
Yes, if it is the main verb of the clause. For example, `He knows` or `They know`.
Yes! You can say `Let the water boil` or `Let it be`.
It is neutral. It's perfectly fine for both business emails and texting friends.
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
Dejar / Que + Subjunctive
Spanish uses subject pronouns in 'que' clauses.
Laisser / Faire
Pronoun placement is before or after the verb depending on the mood.
Lassen
German case marking is more distinct on nouns, not just pronouns.
〜させる (Saseru)
Japanese is synthetic (verb endings), English is analytic (separate words).
دع (Da') / خلّي (Khalli)
Arabic pronouns are attached as suffixes to the verb.
让 (Ràng)
Lack of case inflection in Chinese.
Learning Path
Prerequisites
関連動画
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