～させる／～せる

The causative form (使役形, しえきけい) expresses that someone makes, has, or lets another person do something. Who is doing the action and the relationship between the people involved determines whether it means "make/force" or "let/allow".

Formation

The causative form is conjugated like a ru-verb.

1. Making or forcing someone to do something

When the action is involuntary or the person is being directed by someone with authority, the person who performs the action is marked with を.

Structure: Causer は + Person を + Action させる

2. Letting or allowing someone to do something

When the action is voluntary and the causer gives permission, the person who performs the action can be marked with に.

Structure: Causer は + Person に + Action させる

Note: Whether を or に is used depends on context and nuance. を suggests the causer has control and the action may be unwanted; に suggests more of a permissive or cooperative relationship. In practice, both can be used for transitive verbs, but に is preferred when emphasizing permission.

3. させてください – requesting permission

The causative te-form (させて) combined with ください is used to ask for permission to do something yourself.

This is a polite and common expression in formal and business Japanese.