ておく (Preparation) in Japanese

Overview

The pattern ておく (te oku) combines the て-form with the verb おく (to put/place) to express the idea of doing something in advance, in preparation, or leaving something in a certain state. It is one of the most practical and commonly used て-form compounds in everyday Japanese.

At the B2 level, this pattern helps you express foresight and planning — concepts that are central to how Japanese speakers discuss daily life, work preparation, and thoughtful action. The underlying image is "placing an action down" so that its result remains available for later use.

In casual speech, ておく contracts to とく (toku), which is extremely common and something you will hear constantly in natural conversation.

How It Works

Formation

Component	Pattern
Full form	て-form + おく
Casual contraction	て → とく / で → どく

Conjugation

Form	Full	Casual
Dictionary	ておく	とく
Polite	ておきます	ときます
Past	ておいた	といた
Past polite	ておきました	ときました
て-form	ておいて	といて
Negative	ておかない	とかない

Two Core Uses

Use	Meaning	Example
Preparation	do in advance for future benefit	予約しておく (reserve in advance)
Leaving as is	leave something in a state intentionally	窓を開けておく (leave the window open)

Common Contexts

Context	Example Pattern
Before a trip	荷物をまとめておく (pack in advance)
Before a meeting	資料を準備しておく (prepare materials)
Cooking	材料を切っておく (cut ingredients ahead)
Maintaining state	電気をつけておく (leave the lights on)
Information	調べておく (look it up beforehand)

Examples in Context

Japanese	English	Note
明日のために準備しておきます。	I'll prepare for tomorrow.	Advance preparation
窓を開けておいてください。	Please leave the window open.	Maintaining a state
電話番号を調べといた。	I looked up the phone number in advance.	Casual past
冷蔵庫に入れておきましょう。	Let's put it in the fridge (to keep).	Preserving state
ホテルを予約しておいたほうがいいよ。	You should book the hotel in advance.	Advice
パスポートをコピーしといて。	Make a copy of your passport (in advance).	Casual request
言っておくけど、明日は忙しいよ。	Just so you know, I'm busy tomorrow.	Informing in advance
お金を下ろしておかないと。	I need to withdraw money (ahead of time).	Necessity
この資料、読んでおいてください。	Please read this document (before the meeting).	Business preparation
エアコンをつけておきました。	I left the air conditioning on.	State maintenance
念のため、確認しておきましょう。	Just in case, let's check in advance.	Cautious preparation
買い物リストを作っておこう。	Let's make a shopping list (ahead of time).	Planning

Common Mistakes

Confusing ておく with ている

• Wrong: ドアを開けています。 (when meaning "leave it open intentionally")
• Right: ドアを開けておいてください。
• Why: ている describes an ongoing state without intent. ておく emphasizes that the state is deliberately maintained for a purpose. "The door is open" vs. "Leave the door open."

Forgetting the preparation nuance

• Wrong: 昨日、本を読んでおいた。 (when you just read for pleasure)
• Right: 昨日、本を読んだ。
• Why: ておく implies you read the book for a reason — perhaps for a class or to prepare for a discussion. If you simply read for enjoyment, the plain past is correct.

Using the wrong casual contraction

• Wrong: 買っちゃく or 買ってく
• Right: 買っとく
• Why: The casual contraction of ておく is とく (not ちゃく or てく). 買っておく → 買っとく. Don't confuse this with ていく (てく in casual speech).

Omitting ておく when preparation is implied

• Wrong: 会議の前に資料を読みました。 (when emphasizing advance preparation)
• Right: 会議の前に資料を読んでおきました。
• Why: While grammatically fine, adding ておく explicitly signals that the reading was done as preparation, which is the intended meaning. Japanese speakers expect ておく in preparation contexts.

Usage Notes

ておく is one of the patterns that most clearly reveals the Japanese cultural emphasis on preparation and consideration for others. Using it naturally shows that you think ahead, which is highly valued in Japanese social and business contexts.

The casual とく form is nearly universal in spoken Japanese. In fact, the full ておく can sound overly formal in casual conversation. Among friends, といて (request form) and といた (past) are standard.

In business contexts, ておく appears in nearly every discussion about task management: 確認しておきます (I'll check on that), 報告しておきます (I'll report it), 手配しておきます (I'll arrange it). It signals reliability and proactive work.

The phrase 言っておく (say in advance / give a heads-up) is an extremely common set expression used when delivering a warning or clarification preemptively.

Practice Tips

• Before any event or outing, list three things you need to do in advance using ておく. This mirrors how native speakers naturally plan: 予約しておく, 調べておく, 準備しておく. Making this a mental habit builds the pattern into your thinking.

• Practice the casual contractions by repeating pairs: 読んでおいて → 読んどいて, 買っておく → 買っとく, 調べておいた → 調べといた. The contraction pattern is regular and becomes automatic with repetition.

• In your next conversation with a Japanese speaker, try to use ておく at least twice. Common openings: 聞いておきたいんですが (I'd like to ask in advance) or 言っておくけど (just so you know).

Related Concepts

• Prerequisite: て-Form — the conjugation base for this pattern
• Next steps: てしまう (completion/regret) — another て-form compound expressing completion with emotional weight
• Next steps: てみる (try doing) — て-form compound for experimental actions