English has a small toolkit of separate verbs for getting someone else to act: you make a child eat, let a student leave, have an assistant call. Japanese folds all of that into a single conjugated form — the causative (使役, shieki): させる / せる. One ending covers making, letting, and having, and this page teaches you to build it for every verb class and to set up the causer and causee correctly. The make-versus-let ambiguity baked into that single form is important enough to get its own page; here we nail the formation first.
ru-verbs (ichidan): drop る, add させる
For an ichidan verb, drop the final る and attach させる.
| Dictionary | Causative | Reading |
|---|---|---|
| 食べる (to eat) | 食べさせる | taberu → tabesaseru |
| 見る (to look) | 見させる | miru → misaseru |
| 起きる (to get up) | 起きさせる | okiru → okisaseru |
| 覚える (to memorize) | 覚えさせる | oboeru → oboesaseru |
子供に野菜を食べさせるのは大変だ。
kodomo ni yasai o tabesaseru no wa taihen da
Getting a kid to eat vegetables is hard work.
u-verbs (godan): shift the final -u to -a, add せる
For a godan verb, change the final kana from its -u sound to the matching -a sound, then add せる. This is the same -a stem you already use for the ない-form — which gives you a shortcut below.
| Row | Dictionary | Causative | Reading |
|---|---|---|---|
| く → かせる | 書く (to write) | 書かせる | kaku → kakaseru |
| ぐ → がせる | 泳ぐ (to swim) | 泳がせる | oyogu → oyogaseru |
| す → させる | 話す (to speak) | 話させる | hanasu → hanasaseru |
| つ → たせる | 待つ (to wait) | 待たせる | matsu → mataseru |
| ぶ → ばせる | 遊ぶ (to play) | 遊ばせる | asobu → asobaseru |
| む → ませる | 飲む (to drink) | 飲ませる | nomu → nomaseru |
| う → わせる | 買う (to buy) | 買わせる | kau → kawaseru |
| る → らせる | 帰る (to go home) | 帰らせる | kaeru → kaeraseru |
The う-row is the one to watch: 買う goes to 買わせる, not ×買あせる — the -a partner of う is わ, exactly as in the negative 買わない. This is the only "hidden" consonant in the whole table.
先生は学生に難しい本を読ませた。
sensei wa gakusei ni muzukashii hon o yomaseta
The teacher had the students read a difficult book.
すみません、30分も待たせてしまって。
sumimasen, sanjuppun mo matasete shimatte
Sorry for keeping you waiting a whole thirty minutes.
The irregulars: する → させる, 来る → 来させる
The two irregular verbs each have a fixed causative you simply memorize:
- する → させる (saseru). Note this is not built from a stem — it is its own form. Every compound する-verb inherits it: 勉強する → 勉強させる, 留学する → 留学させる, 練習する → 練習させる.
- 来る（くる）→ 来させる（こさせる）. The kanji stays 来, but the reading shifts from kuru to kosaseru — the same こ- stem as 来ない (konai).
母は妹をアメリカに留学させた。
haha wa imōto o Amerika ni ryūgaku saseta
My mother sent my little sister to study abroad in America.
雨だから、子供を早く帰らせて、犬も家に入らせた。
ame dakara, kodomo o hayaku kaerasete, inu mo ie ni hairaseta
Since it was raining, I sent the kids home early and let the dog in too.
部長がわざわざ私を会議に来させた。
buchō ga wazawaza watashi o kaigi ni kosaseta
The department head went out of his way to make me come to the meeting.
Who is the subject, who takes に or を
The causative reshapes the sentence around a new participant. The causer — the person who makes or lets it happen — becomes the subject. The causee — the one who actually performs the action — is marked with に or を. The rule of thumb depends on whether the underlying verb already has a を-object:
- Transitive verb (already has a を-object): the causee takes に, because を is occupied by the object. → 子供に野菜を食べさせる.
- Intransitive verb (no を-object): the causee usually takes を. → 子供を遊ばせる.
コーチは選手に毎日10キロ走らせている。
kōchi wa senshu ni mainichi jukkiro hashirasete iru
The coach has the athletes run ten kilometers every day.
赤ちゃんを泣かせてしまった。
akachan o nakasete shimatta
I ended up making the baby cry.
That に-versus-を choice is not just bookkeeping — with intransitive verbs it carries real meaning (coercion versus permission), which is why it earns its own page.
The result is an ichidan verb
Whatever route you took, the causative ends in -せる／-させる and therefore conjugates as a brand-new ichidan verb. You never touch the original verb again — just conjugate the causative itself:
| 読ませる (make read) | 来させる (make come) | |
|---|---|---|
| Polite | 読ませます | 来させます |
| Negative | 読ませない | 来させない |
| Past | 読ませた | 来させた |
| te-form | 読ませて | 来させて |
That te-form is the doorway to two hugely common patterns: 〜させてください ("please let me...") and the causative-passive 〜させられる ("to be made to..."). Both are just the causative plus one more auxiliary.
ちょっと考えさせてください。
chotto kangaesasete kudasai
Please let me think about it for a moment.
A note on the short causative
You will hear a shorter causative for godan verbs — 待たす, 行かす, 飲ます instead of 待たせる, 行かせる, 飲ませる — and 〜さす for ichidan (食べさす). This form is informal and leans regional — Kansai and western Japan — though it turns up in casual speech nationwide. It is fine to recognize, but write and speak the standard せる／させる in anything but relaxed conversation.
ちょっと休ましてや。
chotto yasumashite ya
Let me take a little break, would you (short causative, casual/Kansai flavor).
Common mistakes
❌ 先生は学生に本を読みさせた。
sensei wa gakusei ni hon o yomisaseta
Wrong stem — 読む is godan, so the causative uses the -a stem 読ま-, not the masu-stem 読み-.
✅ 先生は学生に本を読ませた。
sensei wa gakusei ni hon o yomaseta
The teacher had the students read a book.
Building a godan causative off the polite/masu-stem (読み-, 書き-, 飲み-) instead of the -a stem is the most frequent formation error. It is 読ませる, not ×読みさせる.
❌ 母は妹を留学しさせた。
haha wa imōto o ryūgaku shisaseta
Wrong — する's causative is the fixed させる; you don't stack it on し-.
✅ 母は妹を留学させた。
haha wa imōto o ryūgaku saseta
My mother sent my sister to study abroad.
❌ 部長が私を会議にきさせた。
buchō ga watashi o kaigi ni kisaseta
Wrong stem — 来る's causative uses the こ- stem (来ない → 来させる), not the masu-stem き-.
✅ 部長が私を会議に来させた。
buchō ga watashi o kaigi ni kosaseta
The department head made me come to the meeting.
来る's forms are notorious for blurring together. Causative = こさせる (来させる); the look-alike こられる (来られる) is instead its passive / potential / honorific. Keep them apart.
❌ 子供を野菜を食べさせる。
kodomo o yasai o tabesaseru
Wrong — a clause can't have two を; the causee of a transitive verb must take に.
✅ 子供に野菜を食べさせる。
kodomo ni yasai o tabesaseru
I make/have the child eat vegetables.
Key takeaways
- ru-verbs: drop る, add させる (食べる → 食べさせる).
- u-verbs: shift -u to -a, add せる (書く → 書かせる, 買う → 買わせる); shortcut — replace ない with せる.
- Irregulars: する → させる, 来る → 来させる（こさせる）.
- The causer is the subject; the causee takes に (transitive) or を (intransitive) — and that choice carries meaning.
- The whole result conjugates as an ichidan verb, feeding 〜させてください and 〜させられる.
Now practice Japanese
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Start learning Japanese→Related Topics
- Causative: Make vs LetN3 — Why the same させる means both 'make (force)' and 'let (allow)' — and how adverbs, benefactive 〜てあげる, and the に／を causee steer it toward coercion or permission.
- Causative Causee: に vs をN3 — How the person made to act is marked in causative sentences — を for many intransitive verbs, に when a transitive object already claims を, and the meaning the choice carries.
- Causative-Passive 〜させられる: Forced ToN3 — The causative-passive — stacking causative onto passive to say you were made to do something against your will, who takes に, and the built-in nuance of reluctance.
- 〜させてください: Asking PermissionN4 — How Japanese builds 'please let me…' and 'may I…' out of the causative — 〜させてください, 〜させてもらえますか, and the business-Japanese workhorse 〜させていただきます.
- Causative 使役: Formation TableN4 — The one-shape reference for 'make / let do': 五段 walk to the あ-row and add せる (書く→書かせる), 一段 add させる (食べさせる), する→させる, 来る→来させる — with the わ-insertion trap and the せる/される mix-up untangled.