～を～に任せる【にまかせる】

The structure ～を～に任せる means "to leave something up to someone/something" or "to entrust something to someone/something." It expresses the idea of delegating a task, decision, or responsibility to another person or letting something take its natural course.

Basic usage: Entrusting to a person

The most common pattern is [Noun (task/thing)] を [Noun (person)] に任せる, where you delegate a task or responsibility to someone.

Leaving something to fate or natural forces

～に任せる can also be used with abstract nouns like うん運 (luck), ながれ流れ (flow), or なりゆき成り行き (course of events) to express letting things happen naturally without trying to control them.

Leaving decisions to someone

When you want someone else to make a decision for you, this pattern is very natural.

Related expressions

• ～に委ねる (ゆだねる委ねる) is a more formal/literary synonym meaning "to entrust" or "to leave to."
• ～に頼む (たのむ頼む) means "to ask someone to do something," which is a more direct request rather than delegation.

Nuance

Using 任せる implies a degree of trust in the person or thing you are entrusting something to. It suggests that you are comfortable stepping back and letting them handle it. It can also convey a sense of resignation when used with abstract concepts like luck or fate.