Causative 使役: Formation Table | Japanese Grammar

This is the single-shape reference for the causative（使役, しえき）— the form that means "make someone do" or "let someone do." The anchor is 書く→書かせる（かかせる, "make/let write"）. A 五段 verb walks its final kana to the あ-row and adds せる; a 一段 verb adds させる; する becomes させる; 来る becomes 来させる（こさせる）. The causative sits on the same あ-row base as the passive, which is exactly why learners confuse せる with される — the last section untangles them for good.

The core split: あ-row+せる vs +させる

A 五段 verb builds the causative on the あ-row (the mizenkei, same base as 書かない and 書かれる), then adds せる:

書く（ka-ku）→ 書かせる（ka-ka-seru）
待つ（ma-tsu）→ 待たせる（ma-ta-seru）
飲む（no-mu）→ 飲ませる（no-ma-seru）

A 一段 verb adds させる to its fixed stem:

食べる → 食べさせる
見る → 見させる

母は毎晩、私に部屋を掃除させた。

haha wa maiban, watashi ni heya o sōji saseta

My mother made me clean my room every night.

子供を公園で好きなだけ遊ばせた。

kodomo o kōen de suki na dake asobaseta

I let the kids play at the park as much as they wanted.

ちょっと考えさせてください。

chotto kangaesasete kudasai

Let me think about it for a moment, please.

The -う verbs insert わ

The same trap as the passive: a 五段 verb ending in the kana う takes わ, not a bare あ. 会う does not become ×会あせる; it becomes 会わせる.

会う（a-u）→ 会わせる（a-wa-seru）
使う（tsuka-u）→ 使わせる（tsuka-wa-seru）
習う（nara-u）→ 習わせる（nara-wa-seru）

娘に小さい頃からピアノを習わせている。

musume ni chiisai koro kara piano o narawasete iru

We've had our daughter take piano lessons since she was little.

くだらない冗談で、みんなを笑わせた。

kudaranai jōdan de, minna o warawaseta

He made everyone laugh with a silly joke.

The full table

Class	Dictionary	Causative	Reading	Rule
五段 -く	書く	書かせる	kakaseru	あ-row + せる
五段 -つ	待つ	待たせる	mataseru	あ-row + せる
五段 -む	飲む	飲ませる	nomaseru	あ-row + せる
五段 -る	座る	座らせる	suwaraseru	あ-row + せる
五段 -う	会う	会わせる	awaseru	あ-row + せる（う→わ）
一段	食べる	食べさせる	tabesaseru	stem + させる
一段	見る	見させる	misaseru	stem + させる
する (irregular)	する	させる	saseru	suppletive
来る (irregular)	来る	来させる	kosaseru	こ + させる

The causative you produce is itself a 一段 verb: 書かせる → 書かせない・書かせます・書かせた・書かせて. Note the 来る reading — 来させる is こさせる, never ×くさせる.

Make vs let, and に vs を

One shape, two readings. 書かせる can mean make write (coercion) or let write (permission); tone and context decide, and 〜てあげる / 〜てくれる often signal the "let" reading. The particle on the person you cause matters:

With an intransitive verb, the causee usually takes を (子供を行かせる, "make the child go") — or に for a softer, more permissive nuance.
With a transitive verb, the object already claims を, so the causee must take に (子供に野菜を食べさせる) — you cannot have two を in one clause.

部長は部下に、その資料を全部作り直させた。

buchō wa buka ni, sono shiryō o zenbu tsukurinaosaseta

The department head made his subordinate redo all of that paperwork.

今日は私に払わせて。この前おごってもらったから。

kyō wa watashi ni harawasete. kono mae ogotte moratta kara

Let me pay today — you treated me last time.

The full に/を decision, with its meaning shifts, is on causative に vs を.

The short causative 〜す / 〜さす

In casual and western-Japan speech you will hear a contracted causative: 書かす for 書かせる, 食べさす for 食べさせる. It is a real, living form — 早く行かす, ちょっと待たして — but it is (informal / regional: western Japan). In writing and standard speech, use the full せる／させる.

ごめん、五分だけ待たしてくれる？

gomen, gofun dake matashite kureru?

Sorry — can you give me just five minutes? (casual short causative)

せる/させる (causative) vs される (passive) — don't confuse

Both forms grow from the same あ-row base, so they look like siblings — but they mean opposite things and take different auxiliaries. Keep the auxiliary straight:

飲む →	Form	Reading	Meaning
Causative	飲ませる	nomaseru	make/let (someone) drink
Passive	飲まれる	nomareru	(it) gets drunk (by someone)
Causative-passive	飲まされる	nomasareru	be made to drink

上司は部下に残業させたが、自分は先に帰った。

jōshi wa buka ni zangyō saseta ga, jibun wa saki ni kaetta

The boss made his staff work overtime but went home first himself. (causative)

Stack the passive on top of the causative and you get the causative-passive (飲まされる, "be made to drink") — its own formation table.

Common mistakes

❌ 二人を会あせてあげたい。

Incorrect — a -う verb inserts わ: 会う → 会わせる. There is no bare 会あ form.

✅ 二人を会わせてあげたい。

futari o awasete agetai

I want to introduce the two of them / bring them together.

❌ 母は私を野菜を食べさせる。

Double を — a clause can't take two. Because 野菜 already claims を, the causee (私) must take に: 私に野菜を食べさせる.

✅ 母は私に野菜を食べさせる。

haha wa watashi ni yasai o tabesaseru

My mother makes me eat vegetables.

❌ 子供に薬を飲めさせた。

Wrong — don't build the causative on the potential/え-row. 飲む is 五段: あ-row + せる = 飲ませる, not ×飲めさせる (that mixes in the potential 飲める).

✅ 子供に薬を飲ませた。

kodomo ni kusuri o nomaseta

I gave the child their medicine (made them take it).

❌ 先生は学生に発表をしさせた。

Wrong — する contracts to させる wholesale; there is no ×しさせる. 発表する → 発表させる.

✅ 先生は学生に発表をさせた。

sensei wa gakusei ni happyō o saseta

The teacher had the students give a presentation.

❌ 部長は部下に残業された。

Meaning-flip — される is the passive ('was worked overtime on'), not the causative. To say the boss 'made' them, use させる: 残業させた.

✅ 部長は部下に残業させた。

buchō wa buka ni zangyō saseta

The department head made his subordinates work overtime.

Key takeaways

書かせる is the anchor. 五段 = final kana to the あ-row + せる; 一段 = stem + させる; する→させる; 来る→来させる（こさせる）.
The -う verbs insert わ (会う→会わせる) — the あ-row of that column is わ.
One shape covers both make (coercion) and let (permission); tone and 〜てあげる/〜てくれる disambiguate.
Particle rule: intransitive causee → を (or に); transitive causee → に (no double を).
The short 〜す/〜さす causative (書かす, 食べさす) is casual/western-Japan; write せる／させる.
Don't confuse せる (causative) with される (passive): same あ-row base, opposite meaning.

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