“nazenara (ba)”: This Is Because 〜 (state the conclusion first, then the reason) [JLPT N2]

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

A connective that gives the result first, then explains the cause

「私は反対だ。なぜなら…」 — the most formal ‘that's because' in an argumentative essay

Writing an essay or report, you state your claim first, then add the reason: 「私はこの案に反対だ。なぜなら、コストが高すぎるからだ」 (I oppose this plan. That's because the cost is too high) — 「なぜなら（ば）」 = that's because, a formal written connector that states the conclusion first, then starts a new clause to add the cause. It's the most formal member of the “conclusion-first, cause-after” family, the first choice for essays and reports. This guide covers its use, the sentence-end echo, and its division of labor with the colloquial 〈なぜかというと〉.

Core: なぜなら = state the conclusion first, then a new clause for the cause

「なぜなら（ば）」 is a connector, used for “stating a conclusion/claim first, then starting a new clause to explain the cause of ‘why it's so'”:

• Structure: [conclusion]. なぜなら、[cause] からだ.
• Example: 地球温暖化は深刻だ。なぜなら、氷河が急速に溶けているからだ。(Global warming is serious. That's because glaciers are melting rapidly.)

「なぜならば」 is the ば-added variant of 「なぜなら」, more literary and formal. The end often echoes with 「〜からだ／〜からである／〜のだ」 (formal writing favors 「からである」).

Feel: “that's because…” — the core is a formal written connector, result-first cause-after, calm, objective, with an argumentative feel — the standard way an essay links “state a claim → give the reason.”

Forms & attachment

Examples in context

• この計画は見直すべきだ。なぜなら、予算を大幅に超えているからだ。(This plan should be reviewed. That's because it far exceeds the budget.)
• 早めの対策が必要である。なぜなら、被害が拡大しつつあるからである。(Early measures are needed. That's because the damage is spreading.)
• 私は彼を信頼している。なぜならば、彼は一度も約束を破ったことがないからだ。(I trust him. That's because he has never once broken a promise.)
• 教育への投資は重要だ。なぜなら、それが国の未来を左右するからだ。(Investment in education is important. That's because it determines the nation's future.)
• 結論は保留したい。なぜなら、まだデータが不十分だからである。(I'd like to reserve judgment. That's because the data is still insufficient.)

⚠️ Common mistakes to avoid

① 「なぜなら」 is a connector — it ‘starts a new clause,' not attached to the cause clause. 「なぜなら」 and 「〜から／〜ので」 differ in position. 「〜から／〜ので」 attaches right after the cause clause (cause-first, result-after): コストが高いから、反対だ (because the cost is high, I oppose it). 「なぜなら」 states the conclusion first, breaks with a period, then starts a new clause (result-first, cause-after): 反対だ。なぜなら、コストが高いからだ。That is, 「なぜなら」 must have a finished conclusion clause before it (broken by 。), and it opens a new clause to add the cause. Don't stuff 「なぜなら」 into the middle of a cause clause like 「から.」

② The end must echo with 「〜からだ／〜からである」; don't drop it. With 「なぜなら」 opening, the sentence end must close with 「〜からだ／〜からです／〜からである／〜のだ」. なぜなら、〜からだ (○) / なぜなら、〜 (×, missing からだ feels incomplete). This is 「なぜなら」's most typical head-tail echo: head 「なぜなら (that's because)」, tail 「からだ (because of the fact that…).」 Formal essays especially favor 「からである」 (more written than からだ). When writing, always pair them: なぜなら〜からである.

③ 「なぜなら」 leans written/formal; rarely used in casual speech. 「なぜなら（ば）」 has a clear written, argumentative, formal color, best for essays, reports, academic writing, formal speeches. In everyday conversation, few people open with 「なぜなら」 to explain a cause — it sounds like writing a paper, too stiff. For colloquial “state the conclusion, then add the cause,” 〈なぜかというと〉 (self-Q&A, friendly) is more natural, or just 「〜から／〜ので／だって.」 Test: essays, formal writing → なぜなら（ば）; everyday speech → なぜかというと／だって. Use なぜなら to give writing an argumentative formality; don't force it in chat.

🔄 Compare: なぜなら／なぜかというと／というのも／〜から

💡 Learning tip

「なぜなら（ば）」 is the most formal, most written member of the “conclusion-first, cause-after” family = the “that's because” of essays — three points: ① it's a connector, ‘starts a new clause' — finish the conclusion (break with a period), then open a new clause with 「なぜなら」 to add the cause; don't stuff it mid-cause-clause like 「から」; ② pair head and tail — head 「なぜなら」, tail must echo 「〜からだ／〜からである」 (essays favor からである, most formal); ③ written formal register — for colloquial “state the conclusion, then add the reason,” the spoken 〈なぜかというと〉 (self-Q&A, friendly) is more natural; don't force 「なぜなら」 in chat. The family's division in one line: written essay = なぜなら, colloquial self-Q&A = なぜかというと, adding background = というのも, stating cause directly = 〜から. Writing an argument or report to “state a claim ＋ give the reason,” the structure 「[claim]. なぜなら、[reason] からである」 is the most standard and persuasive.

❓ Common questions

Q: 「なぜなら」 and 「〜から／〜ので」 both express cause — are they used the same way?

No — they differ in position and word order. 「〜から／〜ので」 = because (attached after the cause clause, cause-first result-after): puts the “cause” first and the “result” after, in one sentence: コストが高いから、この案に反対だ (because the cost is high, I oppose this plan), 雨が降ったので、試合は中止だ (because it rained, the match is cancelled). 「なぜなら」 = that's because (connector, result-first cause-after, new clause): finishes the “conclusion/result” first, breaks with a period, then starts a new clause with 「なぜなら」 to bring out the cause: この案に反対だ。なぜなら、コストが高いからだ (I oppose this plan. That's because the cost is high). Difference: 「から／ので」 is cause-first result-after, within one sentence; 「なぜなら」 is result-first cause-after, across two sentences (conclusion. なぜなら、cause からだ). The word order is exactly reversed. Their register differs too: 「から／ので」 works in speech and writing, the most basic; 「なぜなら」 leans formal written (essays). Test: to “state the cause first then the result, in one breath” use から／ので; to “state the conclusion first, then formally add the reason” (argumentative feel) use なぜなら.

Q: When writing, should I use 「なぜなら」 or 「なぜかというと」?

By the formality of the writing. Both are “state the conclusion, then add the cause,” but the register differs. 「なぜなら（ば）」 = formal written, argumentative register: suited to essays, academic reports, formal commentary, speeches and other styles needing “objective argument.” It's calm and formal, the standard academic link for “state a claim → give the reason,” its end often taking the most written 「からである」: 環境保護は急務である。なぜなら、生態系の破壊が進んでいるからである。 「なぜかというと」 = colloquial, self-Q&A, friendly: suited to blogs, essays, spoken narration, casual explanations, with the conversational feel of “(if you ask) why, it's because…,” reading friendly and unstiff: 私が早起きを始めた理由？　なぜかというと、朝の時間が一番集中できるからです。 Test: formal essays, academic/business reports → なぜなら（ば） (compare 〈なぜかというと〉); blogs, essays, colloquial, wanting a friendlier tone → なぜかというと. A simple criterion: if the whole piece is in argumentative 「である／だ」 style, 「なぜなら〜からである」 harmonizes best; if it's a friendly explanation or blog in 「です・ます」 style, 「なぜかというと〜からです」 is more natural. Choosing the right connector keeps your writing's tone consistent and more professional.

🖊️ Practice Questions (5)

Q1. 「彼を信頼している。___、何度も助けてくれたからだ。」(I trust him. That's because he has helped me many times)

(A) なぜなら　(B) それで　(C) だから　(D) すると

Q2. 「なぜなら」と呼応して文末に最もよく来る形はどれか？

(A) 〇からだ／〇のだ　(B) 〇だろう　(C) 〇ようだ　(D) 〇そうだ

Q3. 「私は早く寝る。なぜなら、明日は試験だからだ。」What is the structure of this sentence?

(A) States the conclusion first, then explains the reason with 「なぜなら〇からだ」 (inverted cause-effect)

(B) States the cause first, then the result

(C) Indicates a turn/contrast

(D) Indicates a parallel relationship

Q4. 「から/ので」と「なぜなら」の語順の違いとして正しいものは？

(A) から/ので＝cause first, then result; なぜなら＝result (conclusion) first, then cause

(B) The two have exactly the same word order

(C) なぜなら can only go at the end of a sentence

(D) から indicates inverted cause-effect

Q5. 「なぜなら」の使い方として不自然な文は？

(A) 行かない。なぜなら、雨だからだ。　(B) 勉強する。なぜなら、合格したいからだ。

(C) この店が好きだ。なぜなら、安いからだ。　(D) なぜなら雨だから、今日は行かない。

Answer Explanations

1. (A) なぜなら ── state the conclusion first, then add the reason with 「なぜなら〇からだ」.

2. (A) 〇からだ／〇のだ ── 「なぜなら〇からだ」 is a fixed correspondence.

3. (A) State the conclusion first, then explain the reason (inverted cause-and-effect) ── なぜなら = inverted cause-and-effect.

4. (A) ── から/ので puts the cause first and the result second; なぜなら puts the conclusion (result) first and the cause second.

5. (D) ── 「なぜなら」 must come after the conclusion sentence, starting a new sentence — it cannot be placed at the very beginning to directly lead into cause + result.