“wo aite ni” Meaning & Usage — With / Against 〜 as the Target [JLPT N3]

Content by NTJ Kuma · Nihongo to Japan editorial team · Updated July 27, 2026

“Dealing with children,” “up against a big company” — doing something with or against someone, with examples. (JLPT N3)

「世界の強豪を相手に戦う」 — 「を相手に」, taking ~ as your opponent/counterpart

「彼は世界の強豪を相手に、堂々と戦った」 (he fought head-on, taking the world's best as his opponents) — 「noun ＋ を相手に(して)」 means “taking someone as your counterpart, engaging in back-and-forth interaction — combat, negotiation, service, and the like,” i.e., “with ~ as your opponent/counterpart.” Used for sports matchups, business, lawsuits, keeping company. This guide covers 「を相手に」's attachment, that “facing a counterpart” feel, and separates it from 「に対して／を対象に」.

Core: setting someone as “the other party in an interaction”

「を相手に」 = “doing something facing/against a counterpart,” with back-and-forth interaction between you and them:

• Combat: 強豪を相手に戦う (fight against a strong opponent).
• Negotiation/business: 外国企業を相手に商売する (do business with foreign firms).
• Service/company: 子供を相手に遊ぶ (play with / entertain children).

Feel: “with ~ as opponent/counterpart,” often implying facing a counterpart of some weight.

How to Connect

See it in context

• 彼は世界の強豪を相手に、堂々と戦った。(He fought head-on against the world's best.) — combat
• 彼女は毎日大勢の記者を相手に、丁寧に受け答えしている。(She faces a crowd of reporters daily, responding politely.) — negotiation
• 外国人観光客を相手に、土産物を売る。(Selling souvenirs to foreign tourists.) — business
• 弁護士は大企業を相手に訴訟を起こした。(The lawyer filed suit against a big corporation.) — litigation
• おばあちゃんは孫を相手に、昔話を楽しんでいる。(Grandma enjoys telling old tales to her grandkids.) — keeping company

⚠️ Easy traps to avoid

① The particle is 「を」, not 「が」. ✗ 強豪が相手に → ✓ 強豪を相手に. The counterpart before 「相手」 is marked with 「を」.

② 「を相手に」 (with interaction/engagement) vs 「を対象に」 (a one-way target, no interaction). を相手に = back-and-forth interaction, engagement (combat, negotiation, play — both sides interact); を対象に = treating a group as a (one-way) target/scope (surveys, research, marketing — no direct engagement). 「学生を対象に調査する (survey targeting students)」 uses を対象に (one-way); 「学生を相手に商売する (do business with students)」 uses を相手に (interaction). Using を相手に for a “non-interactive survey target” is a common error.

③ 「を相手に」 vs 「に対して」. を相手に = with … as opponent/counterpart (face-to-face interaction); に対して = toward…, regarding… (broader — attitude, contrast, ratio). “Facing/serving someone in engagement” → を相手に; “one's attitude toward / regarding something” → に対して.

🔄 Compare: を相手に／に対して／を対象に

💡 Quick takeaway

The core of 「を相手に」 is treating someone as “the other party in an interaction” — there's back-and-forth engagement between you and them: 強豪を相手に戦う (fight a strong opponent), 記者を相手に応対する (handle reporters), 子供を相手に遊ぶ (play with children), 大企業を相手に訴訟 (sue a big company). Three points: ① the particle is を (✗ が相手に); ② separate it from 「を対象に」 — を相手に has “engagement/interaction” (combat, business), while を対象に is a “one-way survey/marketing target” (a questionnaire uses を対象に); ③ colloquially, を is often dropped (子供相手に). It works in both writing (news, verdicts, match reports) and speech, fairly neutral-to-formal. For “facing (a counterpart of some weight) in engagement or service,” を相手に is spot-on.

❓ Questions you might have

Q: How do I tell 「を相手に」 from 「を対象に」?

By “is there back-and-forth interaction/engagement.” 「を相手に」 = someone as a target of ‘engagement, interaction' (both sides give and take): 世界の強豪を相手に戦う (fight strong opponents — mutual contest), 常連客を相手に商売する (do business with regulars — interaction), 子供を相手にサッカーをする (play soccer with kids). 「を対象に」 = treating a group as a ‘(one-way) target/scope' (no direct engagement): 大学生を対象にアンケートを行う (run a survey targeting college students — one-way), 若者を対象にした商品 (a product targeting young people — marketing target). So: has “engagement, interaction” (combat, business, company) → を相手に; a one-way “survey/marketing target” → を対象に. Key test: for surveys, statistics, marketing — where you one-sidedly treat them as a target with no direct give-and-take — use を対象に; for direct interaction, contest, or service, use を相手に.

Q: Can 「を相手に」's 「を」 be dropped? Does it work in both writing and speech?

Yes, it can be dropped, and often is in speech. 「を相手に」 and the colloquially shortened 「相手に」 mean the same: 子供を相手に遊ぶ = 子供相手に遊ぶ (play with children), 素人相手に商売する (do business with amateurs). Dropping 「を」 sounds more casual. As for register: 「を相手に」 works in both writing and speech — it appears in news reports (世界の強豪を相手に), verdicts (大企業を相手に訴訟), match broadcasts, and everyday conversation, a fairly neutral-to-formal expression. Formal writing usually keeps 「を」 (〜を相手に); casual speech often drops it (〜相手に). So don't worry about the setting — its range is wide; just mark the counterpart with 「を」 (or drop it colloquially).

🖊️ Practice Questions (5)

Q1. 「彼は世界の強豪___、堂々と戦った。」(against the world's strongest as opponents)

(A) を相手に　(B) のために　(C) によって　(D) について

Q2. 「を相手に」の前に来るのは?

(A) 名詞　(B) 動詞て形　(C) い形容詞　(D) 疑問詞

Q3. 「子供を相手にサッカーをする」の意味は?

(A) Playing soccer with children as the opponents

(B) For the children's sake

(C) Because of the children

(D) About the children

Q4. 「を相手に」の語感は?

(A) With 〜 as the target / opponent (interaction / confrontation)

(B) Thanks to 〜

(C) Although 〜

(D) Even if 〜

Q5. 接法が正しいのは?

(A) 観光客を相手に商売する。　(B) 観光客を相手にの商売。

(C) 観光客が相手に。　(D) 観光客を相手にして相手。

Answer Explanations

1. (A) を相手に ── Fighting against strong opponents.

2. (A) 名詞 ── A noun precedes it.

3. (A) ── Playing ball with children as the opponent.

4. (A) ── With 〜 as the target / opponent.

5. (A) ── 「名詞＋を相手に」is correct.