Prepositions of time are words that show when something happens. They connect a noun or time expression to another part of the sentence. The most common prepositions of time are at, on, and in, but there are many others such as before, after, during, since, for, until, by, and from…to.

Learning prepositions of time is important because they help make sentences clear and natural. English learners often confuse them because different languages use time expressions differently.

1. Using “At”

We use at for a specific point in time.

Common Uses of “At”

A. Clock Times

The class starts at 9:00.
I woke up at 6:30 a.m.
She arrived at midnight.

B. Specific Moments

We eat together at lunchtime.
He left at sunset.
The streets are quiet at night.

C. Holidays (general period)

I visit my grandparents at Christmas.
People travel a lot at New Year.

Important Idea

Think of at as a tiny point on a timeline.

More Examples

The movie begins at noon.
I usually study at night.
They met at dawn.

2. Using “On”

We use on for days and dates.

Common Uses of “On”

A. Days of the Week

I play basketball on Saturday.
She works on Mondays.

B. Dates

The test is on June 10th.
He was born on March 2, 2010.

C. Special Days

We stayed home on Christmas Day.
People give chocolates on Valentine’s Day.

D. Specific Parts of Days

Use “on” when the day is named.

I saw him on Friday morning.
They arrived on Sunday evening.

Important Idea

Think of on as a surface or a single day on the calendar.

More Examples

We have English class on Tuesday.
The concert is on July 15th.
She called me on Monday afternoon.

3. Using “In”

We use in for longer periods of time.

Common Uses of “In”

A. Months

Flowers bloom in April.
School starts in September.

B. Years

My father was born in 1985.
The company opened in 2001.

C. Seasons

It snows in winter.
We travel in summer.

D. Parts of the Day

I exercise in the morning.
She studies in the afternoon.
We relax in the evening.

(But remember: we say at night, not “in night.”)

E. Longer Time Periods

People traveled by horse in the past.
Technology improved greatly in the 20th century.

Important Idea

Think of in as being inside a large container of time.

More Examples

We moved here in 2020.
The leaves change color in autumn.
He likes reading in the evening.

4. Quick Comparison: At vs. On vs. In

Preposition	Use	Examples
at	specific time	at 7:00, at noon
on	days and dates	on Monday, on May 5th
in	months, years, long periods	in July, in 2024

Example Progression

At 3:00
On Friday
In July

The time period becomes larger as you move from at to in.

5. Using “Before” and “After”

These prepositions show the order of events.

Before

“Before” means earlier than something.

Wash your hands before dinner.
I studied before the test.

After

“After” means later than something.

We went home after the movie.
She slept after lunch.

More Examples

Finish your homework before bedtime.
They celebrated after the game.

6. Using “During”

“During” means something happens within a period of time.

I slept during the flight.
Nobody talked during the exam.

Important Difference

Compare:

I slept during class.
(inside the class period)
I slept after class.
(when class ended)

More Examples

It rained during the concert.
Students must be quiet during lessons.

7. Using “For” and “Since”

These are often used with the present perfect tense.

For

“For” shows a length of time.

I lived here for five years.
She studied English for two hours.

Since

“Since” shows the starting point.

I have known him since 2020.
They have been friends since childhood.

Compare

for three days = duration
since Monday = starting point

More Examples

We waited for an hour.
She has worked there since January.

8. Using “Until” and “By”

Until

“Until” means up to a certain time.

I stayed awake until midnight.
The store is open until 9:00.

By

“By” means no later than a certain time.

Finish your homework by Friday.
Please arrive by 8:00.

Compare

I worked until 8:00.
(I stopped at 8:00.)
I finished the work by 8:00.
(The work was completed before or at 8:00.)

9. Using “From…To” and “Between”

From…To

This shows the beginning and ending times.

School runs from 8:00 to 3:00.
We stayed there from Monday to Thursday.

Between

“Between” is used with two points.

The meeting is between 1:00 and 2:00.
She lived there between 2010 and 2015.

10. Common Mistakes

Mistake 1

❌ I was born on 1999.
✅ I was born in 1999.

Mistake 2

❌ We met in Friday.
✅ We met on Friday.

Mistake 3

❌ I sleep in night.
✅ I sleep at night.

Mistake 4

❌ The party starts at Sunday.
✅ The party starts on Sunday.

11. Tips for Learning Prepositions of Time

A. Memorize Common Patterns

at 6:00
on Monday
in July

Practice these repeatedly.

B. Read and Listen Often

Books, TV shows, and conversations help you hear natural usage.

C. Make Your Own Sentences

Write about your daily schedule.

Example:

I wake up at 7:00.
I study on weekdays.
I relax in the evening.

Conclusion

Prepositions of time help us explain when events happen. The most important ones are:

at for specific times
on for days and dates
in for longer periods

Other prepositions like before, after, during, since, for, until, and by add more detail about timing and duration.

Mastering these prepositions takes practice, but learning the common patterns will make your English sound much more natural and accurate.

時を表す前置詞とは、「いつ」何かが起こるのかを示す言葉です。前置詞は、時間を表す名詞や表現を文の他の部分につなげます。最もよく使われる時の前置詞は at, on, in ですが、ほかにも before, after, during, since, for, until, by, from…to などがあります。

時の前置詞を学ぶことはとても重要です。なぜなら、これらを使うことで文が自然で分かりやすくなるからです。多くの英語学習者は、言語によって時間表現の使い方が違うため、前置詞を混同しやすいです。

1. “At” の使い方

at は「特定の時点」に使います。

“At” の主な使い方

A. 時計の時刻

The class starts at 9:00.
授業は9時に始まります。
I woke up at 6:30 a.m.
私は午前6時30分に起きました。
She arrived at midnight.
彼女は真夜中に到着しました。

B. 特定の瞬間

We eat together at lunchtime.
私たちは昼食時に一緒に食べます。
He left at sunset.
彼は日没時に出発しました。
The streets are quiet at night.
夜は通りが静かです。

C. 祝日（一般的な期間）

I visit my grandparents at Christmas.
私はクリスマスに祖父母を訪ねます。
People travel a lot at New Year.
人々は新年によく旅行します。

ポイント

at は「時間の一点」をイメージしてください。

追加例

The movie begins at noon.
映画は正午に始まります。
I usually study at night.
私はたいてい夜に勉強します。
They met at dawn.
彼らは夜明けに会いました。

2. “On” の使い方

on は「曜日」や「日付」に使います。

“On” の主な使い方

A. 曜日

I play basketball on Saturday.
私は土曜日にバスケットボールをします。
She works on Mondays.
彼女は月曜日に働きます。

B. 日付

The test is on June 10th.
テストは6月10日です。
He was born on March 2, 2010.
彼は2010年3月2日に生まれました。

C. 特別な日

We stayed home on Christmas Day.
私たちはクリスマスの日に家にいました。
People give chocolates on Valentine’s Day.
人々はバレンタインデーにチョコレートを渡します。

D. 特定の日の一部

曜日がある場合は “on” を使います。

I saw him on Friday morning.
金曜日の朝に彼に会いました。
They arrived on Sunday evening.
彼らは日曜日の夕方に到着しました。

ポイント

on は「カレンダー上の一日」をイメージしてください。

追加例

We have English class on Tuesday.
私たちは火曜日に英語の授業があります。
The concert is on July 15th.
コンサートは7月15日です。
She called me on Monday afternoon.
彼女は月曜日の午後に電話してきました。

3. “In” の使い方

in は「長い期間」に使います。

“In” の主な使い方

A. 月

Flowers bloom in April.
花は4月に咲きます。
School starts in September.
学校は9月に始まります。

B. 年

My father was born in 1985.
私の父は1985年に生まれました。
The company opened in 2001.
その会社は2001年に設立されました。

C. 季節

It snows in winter.
冬には雪が降ります。
We travel in summer.
私たちは夏に旅行します。

D. 一日の時間帯

I exercise in the morning.
私は朝に運動します。
She studies in the afternoon.
彼女は午後に勉強します。
We relax in the evening.
私たちは夕方にくつろぎます。

※ただし、「夜」は at night を使い、“in night” とは言いません。

E. 長い時間の期間

People traveled by horse in the past.
昔、人々は馬で移動していました。
Technology improved greatly in the 20th century.
技術は20世紀に大きく進歩しました。

ポイント

in は「大きな時間の中に入っている」イメージです。

追加例

We moved here in 2020.
私たちは2020年にここへ引っ越しました。
The leaves change color in autumn.
秋に葉が色づきます。
He likes reading in the evening.
彼は夕方に読書するのが好きです。

4. At・On・In の比較

前置詞	用法	例
at	特定の時刻	at 7:00, at noon
on	曜日・日付	on Monday, on May 5th
in	月・年・長期間	in July, in 2024

時間の広がり

At 3:00
On Friday
In July

“at” から “in” に行くほど、時間の範囲が広くなります。

5. “Before” と “After”

これらは出来事の順番を表します。

Before

“before” は「〜より前」を意味します。

Wash your hands before dinner.
夕食の前に手を洗いなさい。
I studied before the test.
私はテスト前に勉強しました。

After

“after” は「〜の後」を意味します。

We went home after the movie.
私たちは映画の後に帰宅しました。
She slept after lunch.
彼女は昼食後に寝ました。

6. “During”

“during” は「ある期間の間に」を意味します。

I slept during the flight.
私は飛行中に寝ました。
Nobody talked during the exam.
試験中は誰も話しませんでした。

比較

I slept during class.
授業中に寝ました。
I slept after class.
授業後に寝ました。

7. “For” と “Since”

これらは現在完了形でよく使われます。

For

“for” は「期間」を表します。

I lived here for five years.
私は5年間ここに住んでいました。
She studied English for two hours.
彼女は2時間英語を勉強しました。

Since

“since” は「始まりの時点」を表します。

I have known him since 2020.
私は2020年から彼を知っています。
They have been friends since childhood.
彼らは子どもの頃から友達です。

8. “Until” と “By”

Until

“until” は「〜までずっと」を意味します。

I stayed awake until midnight.
私は真夜中まで起きていました。
The store is open until 9:00.
その店は9時まで開いています。

By

“by” は「〜までに」を意味します。

Finish your homework by Friday.
金曜日までに宿題を終わらせなさい。
Please arrive by 8:00.
8時までに到着してください。

9. “From…To” と “Between”

From…To

始まりと終わりを表します。

School runs from 8:00 to 3:00.
学校は8時から3時までです。
We stayed there from Monday to Thursday.
私たちは月曜から木曜までそこにいました。

Between

2つの時点の間を表します。

The meeting is between 1:00 and 2:00.
会議は1時から2時の間です。
She lived there between 2010 and 2015.
彼女は2010年から2015年の間そこに住んでいました。

10. よくある間違い

❌ I was born on 1999.
✅ I was born in 1999.

❌ We met in Friday.
✅ We met on Friday.

❌ I sleep in night.
✅ I sleep at night.

❌ The party starts at Sunday.
✅ The party starts on Sunday.

11. 学習のコツ

A. よく使うパターンを覚える

at 6:00
on Monday
in July

これらを繰り返し練習しましょう。

B. 英語をたくさん読む・聞く

本やテレビ、会話を通して自然な使い方を学べます。

C. 自分で文を作る

例：

I wake up at 7:00.
私は7時に起きます。
I study on weekdays.
私は平日に勉強します。
I relax in the evening.
私は夕方にくつろぎます。

まとめ

時の前置詞は、「いつ」出来事が起こるかを説明するために使います。

特に重要なのは：

at → 特定の時刻
on → 曜日・日付
in → 長い期間

さらに、before, after, during, since, for, until, by などを使うことで、時間や期間についてより詳しく表現できます。

時の前置詞をマスターするには練習が必要ですが、基本パターンを覚えることで、より自然で正確な英語を話せるようになります。