JLPT N4 Grammar Essentials: 12 Patterns You Must Know

2026年4月23日

JLPT N4 grammar introduces patterns that English speakers find genuinely tricky — not because the vocabulary is hard, but because the logic is different from English. This guide covers the 12 essential N4 grammar patterns with clear rules, examples, and the contrasts that trip people up most.

～てもいい	Permission: It is OK to…	食べてもいい？ — May I eat?
～てはいけない	Prohibition: Must not…	ここで吸ってはいけない — Must not smoke here
～ようになる	Come to be able to / Start doing	泳げるようになった — I became able to swim
～ようにする	Make sure to / Try to	毎日練習するようにしている — I make sure to practice daily
～ために	In order to (intentional goal)	合格するために勉強する — Study to pass
～ように	So that (desired state/result)	忘れないように書く — Write so I don’t forget
～んです / ～のです	Explanation / Background reason	遅れたんです — The thing is, I was late
～らしい	It seems / Apparently (hearsay)	雨が降るらしい — Apparently it’ll rain
～はずだ	Should be / Expected to be	彼は来るはずだ — He should come
～なければならない	Must / Have to	行かなければならない — I have to go
～だろう	Probably / I suppose	明日は晴れだろう — It’ll probably be sunny
～てみる	Try doing (to see how it goes)	食べてみて！ — Try eating it!

TOC

Permission and Prohibition: てもいい vs てはいけない

These two are often taught together and are the most immediately practical N4 grammar patterns.

～てもいい — Permission

Formation: [te-form] + もいい or もいいですか？

ここに座ってもいいですか？
(May I sit here?)

はい、座ってもいいですよ。
(Yes, you may sit.)

窓を開けてもいい？
(Is it OK to open the window?)

～てはいけない — Prohibition

Formation: [te-form] + はいけない / はいけません

ここで写真を撮ってはいけません。
(You must not take photos here.)

授業中にスマホを使ってはいけない。
(You must not use your phone during class.)

Yuka

I kept forgetting: てもいい sounds soft (permission granted), but てはいけない is firm. In real life, native speakers often soften prohibition with ちょっと or という訳には — saying 写真は少し… is more common than 撮ってはいけない in casual situations. But for the JLPT, the grammar form is what matters.
(てもいい = soft permission; てはいけない = firm rule — casual speech softens the prohibition.)

ようになる vs ようにする

Both use ように but they mean very different things. This pair trips up many N4 learners.

～ようになる — Change in state or ability (not volitional)

日本語が話せるようになった。
(I became able to speak Japanese.) [change in ability — happened over time]

毎朝走るようになった。
(I came to run every morning.) [habit change that developed]

～ようにする — Intentional ongoing effort

毎朝走るようにしている。
(I make sure to run every morning.) [deliberate ongoing practice]

遅刻しないようにしている。
(I make sure not to be late.) [ongoing effort]

Key: ようになる = a change happened (result); ようにする = I keep making an effort (process).

んです / のです — The Explanation Marker

This grammar is essential for natural Japanese conversation. It signals that what you are saying is an explanation, background information, or context — not just a raw statement.

Plain statement: 熱があります。(I have a fever.)
With んです: 熱があるんです。(The thing is, I have a fever [explaining why I look unwell / why I can’t come])

Questions with んですか seek background: どうしたんですか？(What happened? / What’s going on with you?)

Rei

んです is the grammar that makes Japanese conversation feel connected. Without it, statements feel like disconnected facts. With it, you are building a shared understanding. At work, starting an explanation with 実は〜んですが (Actually, the thing is…) frames what follows as important context — listeners pay more attention.
(んです signals ‘this is the background you need to understand the situation’ — it creates narrative cohesion.)

らしい vs はずだ — Degrees of Certainty

Both express a degree of uncertainty about future or reported information, but from different sources of evidence.

らしい (rashii)	Hearsay / apparent (from others)	彼は来るらしい	Apparently he’ll come (I heard)
はずだ (hazu da)	Logical expectation (speaker reasons)	彼は来るはずだ	He should come (I expect based on logic)
だろう (darou)	Speaker’s guess/probability	雨が降るだろう	It’ll probably rain (my guess)