The Difference Between〜ように (yō ni) vs 〜ために (tame ni)｜Japanese Grammar (N5–N3)

Alt Text: Joy making a decision [Suru] vs. Joy receiving a notice [Naru]

“I decided to go to Japan.” vs “It was decided that I go to Japan.”
In Japanese, we distinguish between decisions you make and decisions made for you. We use 〜ことにする (Koto ni suru) and 〜ことになる (Koto ni naru). Let’s master the difference!

🗣 Conversation Scene

Joy is talking to Ken about her summer plans and work.

Joy

ケンさん、来月（らいげつ）日本（にほん）へ行くことにしました！
(Ken, I decided to go to Japan next month!)

Ken

いいですね！実（じつ）は私（わたし）も、大阪（おおさか）へ転勤（てんきん）することになりました。
(That’s great! Actually, it has been decided that I will transfer to Osaka, too.)

💡 Explanation

Both phrases connect to the Dictionary Form or Nai-Form of verbs.

Point 1: Koto ni suru (〜ことにする) = My Decision

Use this when YOU decide to do something. It expresses your volition (will).

タバコを辞（や）めることにしました。
(I decided to quit smoking.)
今日（きょう）は家（いえ）にいることにします。
(I decide to stay home today.)

Point 2: Koto ni naru (〜ことになる) = Result / External Factor

Use this when things are decided by others, fate, or rules. Even if you agreed to it, the nuance is “it turned out this way.”

来年（らいねん）、結婚（けっこん）することになりました。
(It has been decided that we will get married. [Reporting the fact])
明日（あした）は雨（あめ）なので、中止（ちゅうし）になることになりました。
(It was decided to cancel because of rain.)

📊 Comparison / Common Mistake

Expression	Subject (Who decides?)	Nuance
〜ことにする (Suru)	I (Me)	Active, Choice, Will
〜ことになる (Naru)	Others / Situation	Passive, Result, Rule

🚧 Joy’s Mistake

❌ Wrong: 会社（かいしゃ）のルールで、制服（せいふく）を着（き）る ことにします。
(If it is a company rule, YOU didn’t decide it.)

✅ Right: 会社（かいしゃ）のルールで、制服（せいふく）を着（き）る ことになっています。
(It is a rule/It has been decided that we wear uniforms.)

🔥 Practice Quiz

Tap to check the answer!

Q1. I decided to study English every day.
(Watashi wa mainichi Eigo o benkyou suru koto ni ______.)

Answer: shimashita (しました)
This is your own decision, so use “suru + koto ni shimashita”.

Q2. My boss told me to transfer to Tokyo.
(Tokyo e tenkin suru koto ni ______.)

Answer: narimashita (なりました)
It was a company order (external decision), so use “naru + koto ni narimashita”.

Q3. School Rule: We must not bring manga to school.
(Manga o motte kite wa ikenai koto ni ______.)

Answer: natte imasu (なっています)
For ongoing rules and regulations, we use the state form “natte imasu”.

Keep practicing with JPLT!