Japanese grammar · ≈ JLPT N3 · Intermediate 1
〜ないことにします~nai koto ni shimasu
decide not to do
Use 「〜ないことにします」 to say you have personally decided not to do something.
How it works

Look at her pushing the snacks aside. She has decided for herself not to eat them in the middle of the night, and uses this pattern to express her decision.

Put the verb in the ない form, then add 「ことにします」. 食べる becomes 食べない, and する becomes しない.

「食べない」 simply says that you will not eat. Adding 「ことにします」 emphasizes that this is your own decision.

In the snack example, 「夜中に」 limits the time: the decision is not to eat snacks in the middle of the night, not to give them up at all times.
Example sentences
- 夜中yonakaにniおかしokashiをo食べないことtabenaikotoにniします。shimasu。
I've decided not to eat snacks in the middle of the night.
- 寝るneru
In a conversation

- A毎日とても忙しくて、過労で倒れそうです。
A: I'm very busy every day and feel like I'm going to collapse from overwork.
- Bそれは大変ですね、今週末
Check yourself
Level 1 · Recognise
Which sentence is correct?
Level 1 · Recognise
Listen and choose the meaning
Level 2 · Build
Put the words in order
I decide not to eat snacks in the middle of the night.
Level 3 · Use
What goes in the blank?
夜中におかしを____。
I've decided not to eat snacks in the middle of the night.
More grammar in this theme
- 〜ないことにしますdecide not to do