N4Chapter 33

Nominalization (の & こと)

Learning Objectives

  • Learn how to nominalize (turn into a noun) entire clauses using の and こと.
  • Understand when の and こと are interchangeable.
  • Learn the specific grammar patterns that ONLY take の.
  • Learn the specific grammar patterns that ONLY take こと.
N4 Context

In English, you can turn a verb into a noun by adding “-ing” (e.g., “I like swimming”) or “to” (e.g., “I like to swim”). In Japanese, we do this by adding の (no) or こと (koto) to the end of a plain-form sentence. This process is called nominalization, and it is essential for talking about actions or facts as concepts!

1. The Basics of Nominalization

To turn a verb, adjective, or entire clause into a grammatical noun, simply put it in the plain form and attach の or こと.

  • 走る (to run) ➔ 走るの (running / the act of running)
  • 日本語を勉強する (to study Japanese) ➔ 日本語を勉強すること (studying Japanese / the fact that one studies Japanese)

For Na-adjectives and Nouns in the present affirmative, you must use な before の or こと.

  • 有名なの (being famous)
  • 学生なこと (being a student - slightly less common)
Grammar Point
Plain Form + の / こと
MeaningTurning an action/state into a noun ('-ing' or 'to do').
Formation:
Verb-Plain + の / こと
Examples (3)
Example

私は本を読むのが好きです。

watashi wa hon o yomu no ga suki desu.

I like reading books (I like the act of reading).

Example

漢字を書くことは難しいです。

kanji o kaku koto wa muzukashii desu.

Writing kanji is difficult.

Example

夜遅く一人で歩くのは危ないです。

yoru osoku hitori de aruku no wa abunai desu.

Walking alone late at night is dangerous.

[!NOTE] In many general sentences (like expressing likes, dislikes, or difficulty), の and こと are completely interchangeable. 読むのが好き and 読むことが好き mean the exact same thing, though の sounds slightly more casual and spoken.

2. When to Use ONLY の

There are specific situations where you must use の, and using こと is grammatically incorrect.

A. Verbs of Perception

If the nominalized action is directly perceived by the senses (seeing, hearing, feeling), you must use の. Verbs like 見る (see), 聞こえる (hear), and 待つ (wait/watch for) require の.

Example

私は田中さんが走っているのを見ました。

watashi wa Tanaka-san ga hashitte iru no o mimashita.

I saw Tanaka running (I saw the physical action of him running).
Example

どこかで誰かが泣いているのが聞こえます。

dokoka de dareka ga naite iru no ga kikoemasu.

I can hear someone crying somewhere.
Example

お湯が沸くのを待っています。

oyu ga waku no o matte imasu.

I am waiting for the water to boil.

B. Helping/Stopping (Direct Action)

When you are directly assisting or preventing physical actions, use の. (e.g., 手伝う - help, 止める - stop/stop someone).

Example

妹が部屋を掃除するのを手伝いました。

imouto ga heya o souji suru no o tetsudaimashita.

I helped my younger sister clean her room.
Example

彼が会社を辞めるのを止めました。

kare ga kaisha o yameru no o tomemashita.

I stopped him from quitting the company.
Example

子供が道路に飛び出すのを防ぎました。

kodomo ga douro ni tobidasu no o fusegimashita.

I prevented the child from jumping out into the road.

3. When to Use ONLY こと

Conversely, there are situations where you must use こと because you are discussing abstract facts, concepts, or using specific fixed grammar patterns.

A. Communication and Thinking

If the main verb relates to communicating facts or internal thought (talking, telling, knowing, believing), use こと. Verbs like 話す (speak), 伝える (convey), and 信じる (believe).

Example

田中さんが結婚したことを知っていますか。

Tanaka-san ga kekkon shita koto o shitte imasu ka.

Do you know (the fact) that Tanaka got married?
Example

明日テストがあることを忘れました。

ashita tesuto ga aru koto o wasuremashita.

I forgot that there is a test tomorrow.
Example

家族がいつも私を応援してくれていることを信じています。

kazoku ga itsumo watashi o ouen shite kurete iru koto o shinjite imasu.

I believe that my family is always supporting me.

B. Fixed Grammar Patterns

In N5 and N4, you learned many patterns that exclusively use こと. You cannot swap these for の.

  • 〜ことができる: Can do… (Ability)
  • 〜ことがある: Have the experience of doing… (Past Experience)
  • 〜ことにする: Decide to do…
  • 〜ことになる: It has been decided that…
Example

私は刺身を食べることができます。

watashi wa sashimi o taberu koto ga dekimasu.

I can eat sashimi. (You cannot say '食べるのができます')
Example

一度も富士山に登ったことがありません。

ichido mo fujisan ni nobotta koto ga arimasen.

I have never climbed Mount Fuji.
Example

健康のために、毎日野菜を食べることにしました。

kenkou no tame ni, mainichi yasai o taberu koto ni shimashita.

I decided to eat vegetables every day for my health.

4. Cultural Insight: Direct vs. Indirect Perception

The choice between の and こと often reflects the Japanese emphasis on the distinction between direct experience and abstract information.

  • Shared Experience (の): When you use の, you are often implying a shared physical space or a direct witness to an event. It feels more immediate and personal. For example, 走っているのを見た means you saw the person’s legs moving in real-time.
  • Information Exchange (こと): Using こと treats the action as a “topic” or a piece of data. It’s used for news, rumors, or historical facts. If you say 結婚したことを聞いた, you are focusing on the news of the marriage, not the ceremony itself.

This nuance is vital in Japanese communication, where showing how you acquired information (via direct observation vs. report) helps establish the reliability and emotional distance of your statement.

Contextual Dialogues

Let’s see how Tanaka and Suzuki use の and こと in their daily conversation.

Talking About Hobbies and News (趣味とニュース)
Suzuki

田中さん、休みの日は何をするのが好きですか。

Tanaka-san, yasumi no hi wa nani o suru no ga suki desu ka.

Tanaka-san, what do you like doing on your days off?

Tanaka

私は写真を撮るのが好きです。私が写真を撮ったのを見たことがありますか。

Watashi wa shashin o toru no ga suki desu. Watashi ga shashin o totta no o mita koto ga arimasu ka.

I like taking photos. Have you ever seen the photos I took?

Suzuki

はい、インスタグラムで見ましたよ。ところで、部長が来月アメリカへ行くことを知っていますか。

Hai, insutaguramu de mimashita yo. Tokorode, buchou ga raigetsu amerika e iku koto o shitte imasu ka.

Yes, I saw them on Instagram. By the way, did you know that the department manager is going to America next month?

Tanaka

えっ？そのことは知りませんでした。驚きました。

E? Sono koto wa shirimasen deshita. Odorokimashita.

Eh? I didn't know that. I am surprised.

Suzuki

そうでしょう？部長が英語を話すのを聞くのは珍しいですね。

Sou deshou? Buchou ga eigo o hanasu no o kiku no wa mezurashii desu ne.

Right? Hearing him speak English is rare.
Weekend Plans (週末の予定)
Hiro

裕美さん、ピアノを弾くことができますか。

Yumi-san, piano o hiku koto ga dekimasu ka.

Yumi-san, can you play the piano?

Yumi

はい、でもあまり上手じゃありません。

Hai, demo amari jouzu ja arimasen.

Yes, but I'm not very good at it.

Hiro

昨日、裕美さんがピアノを弾いているのを聞きましたよ。

Kinou, Yumi-san ga piano o hiite iru no o kikimashita yo.

I heard you playing the piano yesterday.

Yumi

あら、本当ですか？恥ずかしいです。これからは毎日練習することにしました。

Ara, hontou desu ka? Hazukashii desu. Kore kara wa mainichi renshuu suru koto ni shimashita.

Oh, really? I'm embarrassed. I've decided to practice every day from now on.

Hiro

いいですね。時々、ピアノを運ぶのを手伝いますよ！

Ii desu ne. Tokidoki, piano o hakobu no o tetsudaimasu yo!

That's great. I'll help you carry the piano sometimes!

Chapter Summary

Key Takeaways
  • 1Add の or こと to a plain form sentence to turn it into a noun ('Nominalization').
  • 2They are often interchangeable for general statements of preference or description (Like, Hate, Fun, Difficult).
  • 3Use ONLY の for direct sensory perception (seeing, hearing) and physical assistance (helping, stopping).
  • 4Use ONLY こと for abstract facts/communication (knowing, telling) and fixed N4 grammar patterns (ことができる, ことがある).

Knowledge Check

Test your understanding of Nominalization!

Practice Quiz
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Quiz

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What is the function of の and こと after a plain verb?