ておく for Preparation in Japanese

In Brief

Add おく to a verb's て-form to show that an action is done in advance for a later purpose, or that someone deliberately leaves something in a useful state: 調べておく “look it up beforehand,” 開けておく “leave it open.” In casual conversation, ておく often contracts to とく, while でおく contracts to どく.

Overview

The pattern verb て-form + おく connects an action now with a later situation. Perhaps you buy tickets before a trip, write down an address so you will have it when needed, or leave a door unlocked for someone arriving later. English often conveys the same idea with phrases such as “in advance,” “beforehand,” “for later,” “keep,” or “leave,” but Japanese can package that perspective into the verb phrase itself.

This B2 pattern is built directly on the Japanese て-form. The word おく is historically and independently the verb 置く, “to put/place,” but in this grammatical pattern it is normally written in hiragana. It behaves as an auxiliary expression (a verb attached to another verb to add meaning), while still conjugating like an ordinary godan verb.

The important idea is intentional preparation or maintenance, not merely that one action happens earlier than another. 食べた means “ate”; 食べておいた can mean “ate beforehand,” because doing so was useful for what came next. Context often supplies the later purpose, so words such as 前もって “beforehand” are helpful but not required.

How It Works

Basic formation

Put the main action into its て-form, then add おく. If the て-form ends in で, the result is naturally でおく.

Dictionary form	て-form	With おく	Typical meaning
調べる	調べて	調べておく	look up in advance
買う	買って	買っておく	buy in advance / keep ready
開ける	開けて	開けておく	leave open
読む	読んで	読んでおく	read beforehand
する	して	しておく	do in advance
来る	来て	来ておく	come in advance

The first verb contributes the action; おく contributes the viewpoint that its result will matter later or should remain in place.

Conjugate おく, not the first verb

Once the て-form has been made, tense, politeness, and similar changes appear on おく.

Function	Plain	Polite	Meaning
Non-past	しておく	しておきます	do / will do in advance
Past	しておいた	しておきました	did in advance; left done
Negative	しておかない	しておきません	do not / will not do in advance
Request	しておいて	しておいてください	do it beforehand; leave it that way
Suggestion	しておこう	しておきましょう	let's do it in advance
Conditional	しておけば	しておけば	if one does it beforehand

Japanese non-past forms can describe either a habit or a future action. For example, 予約しておきます commonly means “I’ll reserve it in advance,” not “I reserve it.”

Three closely connected meanings

1. Do something in advance

The action prepares for an expected event or need.

• 旅行の前にホテルを予約しておく。 — “Reserve a hotel before the trip.”
• 会議までに資料を読んでおきます。 — “I’ll read the materials before the meeting.”

The future purpose may be stated with のために, 前に, までに, or simply understood from context.

2. Create and keep a useful result

The action produces a state that should remain available.

• 水を冷やしておく。 — “Chill the water and keep it cold.”
• 名前を書いておいてください。 — “Please write your name down [so it is there when needed].”

The translation need not contain “beforehand.” The key is that the result is retained for later.

3. Leave something in its current or chosen state

Here ておく can mean “leave it” rather than change it again.

• 電気をつけておく。 — “Leave the light on.”
• そのままにしておいて。 — “Leave it as it is.”

This use still involves intention: someone chooses to maintain the state.

Casual contractions: とく and どく

In relaxed speech, the vowels in ておく or でおく combine. These contractions are extremely common in conversation.

Full form	Casual contraction	Example
ておく	とく	見ておく → 見とく
でおく	どく	読んでおく → 読んどく
ておいた	といた	買っておいた → 買っといた
でおいた	どいた	読んでおいた → 読んどいた
ておいて	といて	開けておいて → 開けといて
でおいて	どいて	選んでおいて → 選んどいて

The contraction affects the boundary between the て-form and おく. Do not simply remove お from every form: しておきます is normally not contracted in careful polite speech, and しておけば does not become a regular textbook form such as しとけば in formal writing, although contracted forms can occur in casual speech.

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.	Polite promise to prepare in advance
会議の前に、この資料を読んでおいてください。	Please read these materials before the meeting.	Advance task expressed as a request
忘れないように、住所をメモしておいた。	I wrote down the address so I wouldn't forget it.	The saved result is useful later
念のため、薬を持っておこう。	Let's take some medicine with us, just in case.	Volitional form showing precaution
冷蔵庫に入れておきましょう。	Let's put it in the fridge to keep it.	Creates and maintains a useful state
お客さんが来るので、ドアを開けておきます。	Since guests are coming, I'll leave the door open.	A state maintained for a later event
窓を開けておいてください。	Please leave the window open.	The requested result should continue
まだ使うから、パソコンはつけておいて。	I'm still going to use it, so leave the computer on.	Casual request
その箱はそこに置いておいて。	Leave that box there.	置いておく can literally mean place and leave
電話番号なら、もう調べといたよ。	As for the phone number, I already looked it up.	Casual contraction of 調べておいた
帰りの切符も買っとく？	Shall we buy the return ticket too while we're at it?	Casual question; preparation
このことは誰にも言わないでおいてください。	Please don't tell anyone about this.	ないでおく means deliberately refrain
今は結論を出さないでおこう。	Let's avoid reaching a conclusion for now.	Leaves an action undone intentionally
予約しておけば、並ばなくてもいい。	If you reserve in advance, you won't have to queue.	Conditional preparation and later benefit

Common Mistakes

Attaching おく to the dictionary form

• Wrong: 予約するおきます。
• Right: 予約しておきます。
• Why: The first verb must be in its て-form: する becomes して, followed by おきます.

Treating ておく as only “do before”

• Misleading: 窓を開けておいてください。 = “Please open the window beforehand.”
• Better: 窓を開けておいてください。 = “Please leave the window open.”
• Why: The requested result—an open window—must continue. “Beforehand” alone misses that maintained state.

Using ておく for any earlier event

• Unnatural for the intended meaning: 去年、その本を読んでおいた。 (“I happened to read that book last year.”)
• Natural: 試験の前に、その本を読んでおいた。 (“I read that book before the exam.”)
• Why: ておく suggests a purpose, precaution, or useful later result. Use an ordinary past form when merely reporting an earlier event.

Contracting でおく as とく

• Wrong: 読んとく。
• Right: 読んどく。 / 読んでおく。
• Why: A て-form ending in で contracts with おく to どく: 読んでおく → 読んどく.

Mixing levels of formality

• Awkward in a formal email: 資料を読んどいてください。
• Better: 資料を読んでおいてください。
• Why: とく and どく sound conversational. The full form fits polite requests and professional writing better.

Confusing ておく with the separate verb 置く

• Potentially wrong spacing or interpretation: メモして置く。
• Usual grammatical spelling: メモしておく。
• Why: When おく adds preparation or maintained-result meaning, hiragana makes its grammatical role clear. Kanji 置く is generally reserved for the independent meaning “put/place.”

Usage Notes

English translations vary with context

There is no single English suffix equivalent to ておく. Depending on the situation, natural translations include “do in advance,” “get something ready,” “keep,” “leave,” “set aside,” or simply a future verb. 連絡しておきます may be “I’ll let them know,” with the preparatory nuance understood rather than translated word for word.

This difference can cause English-speaking learners to omit ておく. English often relies on context: “I’ll book the table” can imply advance preparation. Japanese speakers may choose 予約しておく to make that preparatory viewpoint explicit.

Requests can concern either an action or a state

〜ておいてください may ask someone to complete a task before a deadline, as in 読んでおいてください, or to maintain a state, as in 開けておいてください. The verb and situation determine which reading is natural. Tone also matters: with a superior, a fuller request such as 〜ておいていただけますか can sound more considerate.

Full and contracted forms

Full ておく is neutral and works in speech and writing. とく and どく are ordinary among friends, family, and colleagues in relaxed conversation, but they are not appropriate everywhere. Contractions can combine with other casual forms—買っとこう “let's buy it in advance,” 読んどけば “if you read it beforehand”—but learners should master the full pattern first and recognize the casual versions before using them freely.

Beyond the Basics / Advanced Use

ておく versus てある

Both patterns can involve a result that remains, but their focus differs.

Pattern	Main focus	Example	Natural interpretation
ておく	Someone's deliberate action for later, or decision to maintain a state	机に資料を置いておく。	Someone will put/keep the materials on the desk for a purpose.
てある	The present resulting state of a deliberate action	机に資料が置いてある。	The materials have been placed on the desk and are there now.

With ておく, the object is commonly marked by を because someone acts on it. With てある, the resulting item is commonly marked by が because the sentence describes its current state. This is a useful contrast, not an absolute translation formula.

ないでおく: deliberately not doing something

Attach おく to ないで, the linking form used here after a negative verb, to mean “refrain from doing” or “leave undone.”

• 今日はお酒を飲まないでおく。 — “I'll refrain from drinking alcohol today.”
• その話には触れないでおいた。 — “I chose not to mention that subject.”

Compare しておかない, which negates the entire preparatory expression and often means “not do it in advance,” with しないでおく, which highlights the deliberate choice not to do it.

Discourse use of 〜は置いておいて

Because 置いておく can literally mean “put something aside and leave it,” expressions such as それは置いておいて also work figuratively: “putting that aside” or “leaving that aside for now.” This is related to the core image but often appears as a fixed conversational transition.

• 冗談は置いておいて、本題に入りましょう。 — “Joking aside, let's get to the main point.”

Practice Tips

1. Plan a real event in Japanese. Before a trip, meeting, or dinner, write five things to do using 〜ておく: 切符を買っておく, 店を予約しておく, and so on. A real later purpose makes the nuance memorable.
2. Make state pairs. Choose verbs such as 開ける, 閉める, つける, and 消す, then say what should remain that way: 電気をつけておく “leave the light on.” This prevents you from learning ておく as only “beforehand.”
3. Train your ear for contractions. Turn full forms into conversational ones—買っておいた → 買っといた, 読んでおく → 読んどく—then practice expanding them again. Recognition is especially important because subtitles and everyday speech frequently use the shorter forms.

Related Concepts

• Prerequisite: て-Form — you need the correct て-form before adding おく.