“tsuyo maru” vs. “tsuyo meru”：Have You Been Correctly Using These?

Japanese has many verb pairs that look nearly identical but differ in a crucial way: one is intransitive (the subject changes on its own) and the other is transitive (someone causes the change). One of the most useful pairs to master at the intermediate level is 強まる（つよまる） and 強める（つよめる）. Both relate to strength increasing, but who or what causes it makes all the difference.

Yuka

Rei, my textbook has both 強まる and 強める, but I always mix them up. They both mean “become stronger,” right?

Rei

Close! 強まる means “to become stronger” on its own — no one is causing it. 強める means “to make something stronger” — someone or something is actively increasing the strength. The difference is intransitive vs. transitive. Think: 強まる = it strengthens itself, 強める = you strengthen it.

At a Glance

強まる（つよまる）— Something Becomes Stronger on Its Own

強まる（つよまる） is an intransitive verb — it describes a change that happens without an external agent actively causing it. The subject simply becomes stronger, more intense, or more powerful. It is commonly used with weather phenomena (wind, rain), emotions (desire, resolve), and social/political forces (opposition, pressure). Because it describes natural or spontaneous change, it appears frequently in news and weather reporting.

Formation note: 強まる uses the -まる suffix, which is the standard marker for intransitive verbs of this type. The paired transitive form uses -める.

Example 1
Japanese: 夕方から風が強まるでしょう。
Romaji: Yuugata kara kaze ga tsuyomaru deshou.
English: The wind will likely strengthen from the evening.

Example 2
Japanese: 批判が強まるにつれて、政府は対応を変えた。
Romaji: Hihan ga tsuyomaru ni tsurete, seifu wa taiou wo kaeta.
English: As criticism intensified, the government changed its response.

Example 3
Japanese: 雨の勢いが強まってきた。
Romaji: Ame no ikoi ga tsuyomatte kita.
English: The intensity of the rain has been increasing.

Yuka

So 強まる is used when nothing is being “done” to make it stronger — it just happens naturally? Like a storm intensifying?

Rei

Exactly. Intransitive verbs describe changes that occur on their own. No one is “doing” the strengthening — it just happens. Weather, emotions, social trends — these all 強まる naturally.

強める（つよめる）— Someone Actively Makes It Stronger

強める（つよめる） is a transitive verb — it requires a subject (agent) who is actively increasing the strength of an object. When someone strengthens their resolve, a company strengthens its ties, or a government strengthens regulations, 強める is the verb to use. It takes an object marked with を. Because it implies intentional action, it is common in news, business, and motivational contexts.

Formation note: 強める uses the -める suffix, which marks transitive verbs in this paired set. It is a Group 2 (ichidan) verb: 強め + る.

Example 1
Japanese: 彼女は意志を強めて、最後まであきらめなかった。
Romaji: Kanojo wa ishi wo tsuyomete, saigo made akiramenakatta.
English: She strengthened her resolve and did not give up until the end.

Example 2
Japanese: 両国は結びつきを強めることに合意した。
Romaji: Ryoukoku wa musubitsuki wo tsuyomeru koto ni goui shita.
English: Both countries agreed to strengthen their ties.

Example 3
Japanese: セキュリティを強めるために対策を導入した。
Romaji: Sekyuriti wo tsuyomeru tame ni taisaku wo dounyuu shita.
English: Measures were introduced to strengthen security.

Yuka

So when a person or organization is deliberately making something stronger, I use 強める? Like “we will strengthen our team.”?

Rei

Yes! チームを強める (chimu wo tsuyomeru) — “to strengthen the team” — is a perfect example. There is an agent (we), an action (strengthening), and an object (the team). That is the transitive structure.

Common Mistakes

Side-by-Side Comparison

More Transitive / Intransitive Pairs Like This

This -まる / -める pattern appears across many Japanese word pairs. Once you learn the pattern, you can predict which form to use for many similar words:

– 弱まる（よわまる）/ 弱める（よわめる）— weaken (naturally) / weaken (intentionally)
– 高まる（たかまる）/ 高める（たかめる）— rise (naturally) / raise (intentionally)
– 深まる（ふかまる）/ 深める（ふかめる）— deepen (naturally) / deepen (intentionally)
– 固まる（かたまる）/ 固める（かためる）— harden (naturally) / harden (intentionally)

Decision Flowchart

Is someone or something actively causing the strengthening?
        |
       YES --> Use 強める（つよめる）+ を
        |
        NO
        |
Does it happen naturally, without a deliberate agent?
        |
       YES --> Use 強まる（つよまる）
        |
        NO
        |
Is there a subject + を + verb structure?
        |
       YES --> Use 強める（つよめる）
        |
       NO --> Use 強まる（つよまる）

Quick Quiz

Yuka

Let me try! 強まる or 強める — which is correct?

Rei

Ask yourself: is someone causing it, or does it happen naturally?

Q1: 台風の勢いが___ています。
A1: 強まっ (tsuyomatte) — the typhoon intensifies naturally (intransitive).

Q2: 彼は練習を通じて体を___た。
A2: 強め (tsuyometa) — he deliberately strengthened his body through training (transitive).

Q3: 社会的な圧力が___につれ、会社は方針を変えた。
A3: 強まる (tsuyomaru) — social pressure intensifies on its own (intransitive).

Q4: 政府は規制を___ことを決めた。
A4: 強める (tsuyomeru) — the government deliberately strengthens regulations (transitive).

Q5: 彼女への気持ちが日に日に___いる。
A5: 強まって (tsuyomatte) — feelings grow stronger naturally over time (intransitive).

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