間・
Both forms place one situation inside a period of time. Use 間 when the situation continues or recurs across that period, and 間に when an event, change, or completed task fits within it.
The key choice
First identify period A, then ask what situation B does inside it. If B continues, remains true, or happens repeatedly across the relevant stretch of A, choose 間. If B has a boundary—something happens, changes, or gets finished within A—choose 間に. English words such as “while” and “during” do not by themselves tell you which form to use.
How the two forms divide the time
Swipe sideways to compare every column.
| Form | How B occupies period A | Typical kinds of B |
|---|---|---|
| 間 or 間は | B extends or recurs across the relevant duration. | Continuing states, ongoing activities, habits, and repeated actions |
| 間に | B occurs or reaches completion somewhere within the duration. | Events, changes, achievements, and completed tasks |
The same period, two different views
In the first sentence, helping is repeated throughout the vacation. In the second, finishing the project is one completed achievement within that vacation.
夏休みの間、祖父の店を毎日手伝った。
Throughout summer vacation, I helped at my grandfather's shop every day.
AnalyzeThe action recurs across the period, so 間 is natural.
夏休みの間に、自由研究を終わらせた。
I finished my independent research project during summer vacation.
AnalyzeThe project reaches completion within the period, so 間に is natural.
After a clause
子どもが小さい間、家族でよく公園へ行った。
While the children were young, we often went to the park as a family.
AnalyzeGoing to the park is a repeated activity across the period when the children are young.
母が買い物をする間に、私は夕食を作った。
While my mother went shopping, I made dinner.
AnalyzeMaking dinner takes time, but it is presented as a completed task inside the shopping period.
More examples
会議の間、携帯電話を切っておいてください。
Please keep your mobile phone turned off during the meeting.
Analyze留守の間、隣の人が猫の世話をしてくれた。
While I was away, my neighbor took care of my cat.
Analyze授業の間、ずっと窓の外を見ていた。
I kept looking out the window throughout the class.
Analyze赤ちゃんが昼寝をする間に、洗濯を済ませた。
I finished the laundry while the baby took a nap.
Analyze一週間の間に、三冊の本を読んだ。
I read three books within one week.
Analyze冬休みの間に、運転免許を取った。
I got my driver's license during winter vacation.
Analyze