～ておく

How to form it

• Verb (て-form) + おく
• Past: ～ておいた
• Casual contraction: ～とく (見とく)

Register: Neutral

Explanation

Shows that something is done in advance for a later purpose, or that something is left in a state.

It stresses preparation or leaving something as is. The result is often described with ～てある.

Examples

1. 旅行の前に、ホテルを予約しておく。

   りょこうのまえに、ホテルをよやくしておく。

   I'll book a hotel before the trip.

2. 明日の会議のために、資料を読んでおくといいですよ。

   あしたのかいぎのために、しりょうをよんでおくといいですよ。

   It is good to read the materials in advance for tomorrow's meeting.

3. 暑いので、窓は開けておくつもりです。

   あついので、まどはあけておくつもりです。

   It's hot, so I plan to leave the window open.

Compare with

• ～てある: ～てある describes the resulting state.
• ～てしまう: ～てしまう shows completion or regret.

Common mistakes

• Using ～ておく for an action that has neither a preparation purpose nor the meaning of deliberately leaving something as it is.
• Mixing it up with ～てある.