“〜te oku”: Do in Advance, Prepare for the Future (essential at N4) [JLPT N4]
Content by NTJ Kuma · Nihongo to Japan editorial team · Updated July 27, 2026
「旅行前にホテルを予約しておく」 — get it done ahead of time, for later.
「旅行前にホテルを予約しておく」 — 「〜ておく」, doing in advance for the future
Before a trip, you 「ホテルを予約しておく」 (book the hotel ahead) — 「(verb て-form) ＋ おく」 means “do in advance, prepare beforehand (for a future purpose).” It has a second sense too: “leave as is, keep a state” (そのままにしておく). This guide covers 「ておく」's two uses, the colloquial contraction 「とく」, and how it differs from the look-alike 「てある」 (its own guide).
Core: do in advance for the future (or keep a state)
「〜ておく」 has two uses:
- ① Prepare in advance (do ahead for a future purpose): 予約しておく (book ahead), 買っておく (buy ahead), 調べておく (look up ahead).
- ② Leave, keep a state (maintain as is): 窓を開けておく (leave the window open), そのままにしておく (leave it as it is).
Colloquially contracts to 「〜とく／〜どく」: やっとく (= やっておく), 飲んどく (= 飲んでおく).
How to Connect
| Form | Nuance | Example |
|---|---|---|
| verb て-form ＋ おく | do in advance | 予約しておく |
| (keep a state) | leave, maintain | 開けておく |
| colloquial contraction | 〜とく／どく | やっとく |
實用例句
- 旅行の前に、ホテルを予約しておいた。(I booked the hotel ahead before the trip.) — prepare
- 忘れないうちに、メモしておこう。(Let me note it down before I forget.) — prepare
- 客が来るから、部屋を掃除しておく。(Guests are coming, so I'll clean the room ahead.) — prepare
- 暑いから、窓を開けておいて。(It's hot, so leave the window open.) — keep a state
- じゃ、予約はやっとくね。(OK, I'll take care of the booking.) — colloquial (とく)
⚠️ Common mistakes to avoid
① 「ておく」 vs 「てある」. ておく = the (person's) act of doing ahead (予約しておく = (I) book ahead); てある = the state left after doing (予約してある = it's (already) booked). One is “the act of preparing,” the other “the prepared result” (see the 〈てある〉 guide).
② The colloquial 「とく／どく」 is very common. 〜ておく→〜とく (やっとく, 買っとく), 〜でおく→〜どく (読んどく, 飲んどく). Casual speech almost always uses the contraction — your listening must catch “とく = ておく.”
③ Don't miss the second sense, “leave as is.” 「そのままにしておく (leave it as it is)」, 「電気をつけておく (leave the light on)」 — this is “keep the current state,” not “prepare.” Tell by context.
🔄 Compare: ておく／てある／てみる
| Form | Nuance | Example |
|---|---|---|
| 〜ておく | do ahead (the act of preparing) | 買っておく |
| 〜てある | the state after doing (transitive) | 買ってある |
| 〜てみる | try doing (see the result) | 買ってみる |
💡 The key point in use
The core of 「ておく」 is “do it ahead, for the future” — 旅行前予約しておく (book ahead), 会議前に資料を準備しておく (prep materials ahead), a practical “plan ahead” feel. Don't miss the second sense: “leave, keep a state” (窓を開けておく = leave the window open, そのままにしておく = leave it as is). You must catch the contraction in speech: 〜とく (= ておく), 〜どく (= でおく) — 「買っとく (buy ahead), 読んどく (read ahead)」 are super everyday. The difference from 「てある」: ておく is “the act of preparing,” てある is “the prepared state.” To dive into other て-auxiliaries like てみる／てしまう, see the 〈てみる complete〉 guide.
❓ Questions you might have
Q: How do I tell 「ておく」 from 「てある」?
By action vs state. 「ておく」 = the (person's) act of “doing” ahead for the future (旅行前にホテルを予約しておく = (I) book the hotel ahead — stressing the act of preparing). 「てある」 = the “state left” after the action (ホテルが予約してある = the hotel is (already) booked — stressing the “prepared” state). The relationship: first 「予約しておく (do the preparing)」, and once done it becomes 「予約してある (the prepared state)」. One is the action, the other the resulting state (see the 〈てある〉 guide).
Q: What's the colloquial contraction 「とく」 of 「ておく」?
In speech 「〜ておく」 often shortens to 「〜とく」, and 「〜でおく」 to 「〜どく」: やっておく→やっとく (do ahead), 買っておく→買っとく (buy ahead), 読んでおく→読んどく (read ahead), 飲んでおく→飲んどく (drink/prep ahead). Casual speech almost always uses the contraction, e.g. 「宿題やっとくね (I'll get the homework done)」, 「予約しとく (I'll book ahead)」. Get used to “とく／どく = ておく／でおく” for both listening and speaking.
🖊️ Practice Questions (5)
Q1. 「旅行前にホテルを予約し___。」 (book the hotel in advance) Which fits the blank?
(A) てある (B) ておいた (C) てしまった (D) ていた
Q2. 「忘れないうちに、メモし___ほうがいい。」 (better to note it down before forgetting) Which fits the blank?
(A) ておく (B) てある (C) てくる (D) ていく
Q3. What is the colloquial contraction of 「ておく」?
(A) てる (B) とく (C) とった (D) てく
Q4. 「ドアを開け___。」 (keep the door open) Which is most natural?
(A) ておく (B) てしまう (C) てある (D) てみる
Q5. What is the difference between 「窓が開けてある」 and 「窓を開けておく」?
(A) exactly the same
(B) てある = a state (someone opened it); ておく = a deliberate preparation done in advance
(C) てある = past; ておく = future
(D) てある is more polite than ておく
Answer Explanations
1. (B) ておいた ── the past tense of ておく is ておいた. 「予約しておいた」 = booked in advance (preparation before the trip).
2. (A) ておく ── doing something before you forget = a typical use of ておく. 「メモしておく」.
3. (B) とく ── colloquial contraction: ておく → とく. 食べておく→食べとく.
4. (A) ておく ── keeping the door in an open state (deliberately leaving it open) uses ておく. てある is a "resulting state".
5. (B) ── てある = a state (someone opened it, it's now open); ておく = a deliberate action done in advance. 「窓が開けてある」 (someone opened it, it's now open) vs 「窓を開けておく」 (I'll open it and keep it that way).