How to Conjugate Japanese Causative Form させる

The causative form is a type of Japanese verb form that often ends in 〜させる. It gives the verb the meaning of "to cause someone or something to do something."

What Is the Causative Form?

Causative form 〜させる refers to verbs ending in either 〜させる or kana from the あ column + せる—this includes verbs like 食べさせる (to have/let someone eat), 飲ませる (to have/let someone drink), or 来させる (to have/let someone come). When you want to say someone (or something) caused someone (or something) else to do something, you conjugate a verb into this form.

If you are looking for more details about its meanings and functions, check out our usage page on causative 〜させる.

Now let's take a look at how to convert Japanese verbs to the causative させる form.

Godan	会う　→　会わせる立つ　→　立たせる写す　→　写させる代わる　→　代わらせる書く　→　書かせる泳ぐ　→　泳がせる死ぬ　→　死なせる学ぶ　→　学ばせる休む　→　休ませる
Ichidan	食べる　→　食べさせる起きる　→　起きさせる閉じる　→　閉じさせる
Irregular	来る（く　）　→　来させる（こ　　　）する　→　させる

Godan Verbs

For godan verbs, replace the ending vowel from the う column on the kana chart to its corresponding あ column kana and add せる. So if the original ending is む, the new ending will be 〜ませる. If it's つ, your new causative ending will be 〜たせる. Let's try conjugating the verb 読む (to read) into its causative form (because we are causing you to read this page right now).

読む　+　ま　+　せる　=　読ませる

Now what about 買う (to buy)? This one looks even easier because the verb itself ends with う, doesn't it? But making 買う into 買あせる is actually incorrect. In this case, it becomes 買わせる.

❌ 買う　+　あ　+　せる　=　買あせる

⭕️ 買う　+　わ　+　せる　=　買わせる

Why is this? This is because all the verbs ending in 〜う used to end in 〜ふ in classical Japanese—hundreds of years ago. So the verb 買う in classical Japanese is 買ふ, and it changes to 買はせる. Unlike modern Japanese, these ancient ふ and は sounds are pronounced as う and わ, just like the particle は is pronounced わ today. The modern 〜う ending verbs still conjugate the same as the classical 〜ふ ending verbs, so the causative form of 買う is actually 買わせる. For the same reasons, the causative form of 会う (to meet) is 会わせる and 縫う (to sew) is 縫わせる.

Ichidan Verbs

For ichidan verbs, just replace the 〜る ending with 〜させる. For example, 食べる (to eat) becomes 食べさせる.

Irregular Verbs

There are only two irregular verbs to remember. Not bad! The causative form of 来る（く　） (to come) is 来させる（こ　　　）, and する (to do) becomes a totally-different-looking verb: させる.

Conjugations of Causative Shorter Form (Verb Conjugation)

Although many textbooks don't cover this, there is actually another set of conjugations to make verbs causative. The reason that isn't always covered is that the usage is limited to casual speech or dialects like Kansai-ben. Since the verb in this form ends in 〜さす or あ-column kana plus す, we call it the causative shorter form. In order to make this form, just replace the 〜せる of normal causative forms with す. Here is the chart so that you can compare it to the normal causative form.

Godan	会う　→　会わす立つ　→　立たす写す　→　写さす代わる　→　代わらす書く　→　書かす泳ぐ　→　泳がす死ぬ　→　死なす学ぶ　→　学ばす休む　→　休ます
Ichidan	食べる　→　食べさす起きる　→　起きさす閉じる　→　閉じさす
Irregular	来る（く　）　→　来さす（こ　　）する　→　さす

Although usage in this form is limited, you may still hear certain words used this way as some have settled into common use as independent 〜す-ending verbs—for example 泳がす (to let someone move around freely), 寝かす (to put someone to bed, to lay something down), or 沸かす (to boil water).