“〜nara iza shirazu”: If It Were 〜, That'd Be One Thing, But… [JLPT N1]

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

「昔ならいざしらず、今は難しい」「子供ならいざしらず大人が泣くな」 — if it were that case it'd be different, but the current situation isn't.

「子供ならいざしらず、大人が泣くな」 — if it were ～ that'd be one thing, but…

To first concede “(in that case) it'd be understandable,” then turn to point out “but now it's different,” Japanese uses a contrastive pattern — 「昔ならいざしらず、今の時代にそんなやり方は通用しない (if it were the old days that'd be one thing, but such a method won't fly nowadays).」 「〜ならいざしらず」 = if it were ～ that'd be one thing, but…, ～ aside. It first sets an exception, then turns to negate the present. This guide clarifies its core of “set an exception ＋ turn,” separating it from 「は別として.」

Core: if it were ～ (that case) that'd be one thing, but (the present) is different／shouldn't ～

「noun／plain form ＋ ならいざしらず」 means “if it were ～ that'd be one thing, (in that case) it'd be understandable, but…” — first citing an exception that “(in that case) is understandable, would pass,” then turning to point out “but (the present, actual case) is different, so it won't do／shouldn't ～”:

• 新人ならいざしらず、ベテランがこんなミスをするとは (if it were a newcomer that'd be one thing, but for a veteran to make such a mistake…).
• 一度や二度ならいざしらず、毎回遅刻するのは許されない (once or twice would pass, but being late every time isn't allowed).
• 昔ならいざしらず、今はネットで何でも調べられる (if it were the old days that'd be one thing, but now you can look up anything online).

Feel: the core is “(if it were) ～ (that case), that'd be one thing／would pass; but (the present case) is different, so it won't do／shouldn't ～” — it first concedes an exception (that case is okay), then turns to negate the present (but this case won't do). 「いざ知らず」 is a classical residue, literally “(in that case) I don't know (how it'd be) = aside, that's another matter.” In English: “if it were ～ that'd be one thing, but…, ～ aside (but…).”

Forms & attachment

Example sentences

• 素人ならいざしらず、プロがこんな失敗をするとは信じられない。(If it were an amateur that'd be one thing, but for a pro to fail like this is unbelievable.)
• 若い頃ならいざしらず、この年で徹夜はきつい。(In one's youth that'd be one thing, but at this age all-nighters are tough.)
• 一人ならいざしらず、家族がいる身では冒険はできない。(Single that'd be one thing, but as someone with a family, I can't take risks.)
• 知らなかったならいざしらず、知っていて黙っていたのは問題だ。(Not knowing would be one thing, but knowing and staying silent is a problem.)
• 緊急時ならいざしらず、平時にこの規則を破るのは許されない。(In an emergency that'd be one thing, but breaking this rule in normal times isn't allowed.)

⚠️ Where learners slip up

① The core is ‘first set an exception (that case is okay), then turn to negate the present.' This is 「ならいざしらず」's core feel. Its logic is two-stage: ① first concede, admit an exception — “if it were ～ (that case), that'd be another matter／would pass／would be understandable”; ② then turn, negate the present — “but (the present, actual case) is different, so it won't do／shouldn't／isn't allowed”: 新人ならいざしらず、ベテランがこんなミスを (a newcomer would pass, but a veteran (of all people) making such a mistake — first admitting “a newcomer's okay,” then negating “a veteran isn't”). It's often to contrast an “understandable exception” with an “unacceptable present,” the latter mostly with negation, criticism, contrast. Test: to say “(if it were) ～ (that) another matter, but (the present) won't do／is different” → ならいざしらず.

② 「いざ知らず」 = the classical ‘I don't know (how it'd be)' = another matter. This is the origin. 「ならいざしらず」's 「いざ知らず」 is a classical residue, literally “(in that case,) I don't know (how it'd be) = that aside, another matter.” So 「子供ならいざしらず」 = “(if it were) a child, (how it'd be) I don't know／another matter” = “a child aside.” 「いざ」 is a classical interjection, 「知らず」 = don't know. The whole 「ならいざしらず」 extends to “(that case) another matter, aside.” Test: 「ならいざしらず」 = “(if it were ～) that another matter, aside” (いざ知らず = the classical “I don't know／another matter”).

③ Separate it from 「は別として／はともかく」 — ならいざしらず carries more of a ‘(the exception) is okay, but (the present) won't do' contrast and negation. Both express “～ aside, another matter,” but differ in feel. 「〜ならいざしらず」 = if it were ～ that'd be one thing (first setting a ‘would pass' exception, then turning to negate the present, with clear contrast and criticism): 昔ならいざしらず、今は違う (the old days would be one thing, but now it's different — strongly contrasting “then okay／now not”). It carries the contrast, negation “(that exception) is understandable, but (the present) won't do.” 「〜は別として／はともかく」 = ～ aside, setting ～ apart (shelving some topic for now, more neutral): 味は別として、見た目は綺麗だ (taste aside, it looks pretty — shelving “taste” for now, talking of something else). It's more neutral, just “shelving ～ for now, talking of something else,” without the “exception okay／present not” contrast-negation. Difference: 「ならいざしらず」 = set an exception then turn to negate the present (with contrast, criticism); 「は別として」 = shelve some topic for now (more neutral). Test: to say with contrast, negation “(that) another matter, but (this) won't do” → ならいざしらず; to just neutrally “～ aside, talking of something else” → は別として.

🔄 Compare with similar forms: ならいざしらず／は別として／はともかく／ならまだしも

💡 How to remember this

「〜ならいざしらず」 = if it were ～ that'd be one thing, ～ aside, but… — three points: ① the core is ‘first set an exception (that's okay), then turn to negate the present (but this won't do)' — with clear contrast and criticism (新人ならいざしらず、ベテランがミスを = a newcomer okay, a veteran not); ②「いざ知らず」 = the classical ‘I don't know／another matter'; ③ separate it from 「は別として (neutrally shelving a topic)」 — ならいざしらず carries contrast-negation. This pattern well expresses that “concede a step, then forcefully rebut” contrast — 「昔ならいざしらず、今は…」 renders, forcefully, that contrast and criticism of “(that case) would pass, but (the present) is different.” To say with contrast, criticism “(that) another matter, but (this) won't do,” 「ならいざしらず」 is spot-on.

❓ Questions you might have

Q: What does 「昔ならいざしらず」 mean? Why ‘another matter'?

「昔ならいざしらず」 = “if it were the old days that'd be another matter／the old days would pass (but now it's different).” Its logic is to first concede, admit “(if it were the old days,) that'd be understandable, would pass,” then (implying or stating) turn to “but the present is different”: 昔ならいざしらず、今の時代にそんな考えは古い (the old days would be another matter, but nowadays such thinking is outdated — first admitting “the old days okay,” then negating “now not”). 「いざ知らず」 is a classical residue, literally “(in that case, how it'd be) I don't know” = “aside, another matter.” So 「昔ならいざしらず」 = “the old days (how it'd be) I don't know／aside = the old days another matter,” implying “but now it's not so.” Its point is to contrast ‘(the exceptional) that case' with ‘(the to-be-negated) present case' — first admitting the exception, then highlighting the present's difference, its shouldn't-ness. Test: on seeing 「〜ならいざしらず,」 read it as “if it were ～ (that case) another matter／would pass, but (the present) is different／won't do”; it's a “set an exception, then turn to negate the present” contrastive pattern, the latter clause often a negation or criticism of the present.

Q: What's the difference between 「ならいざしらず」 and 「は別として」? Both ‘～ aside'?

The difference is ‘whether there's a ‘contrast ＋ negate the present' sense.' 「〜ならいざしらず」 = if it were ～ that'd be one thing (first setting a ‘would pass' exception, then turning to negate the present, with clear contrast, criticism): it's not just “aside,” but first admits an exception (that case is okay), then forcefully turns to negate the present (but this case won't do), with clear contrast and criticism: 新人ならいざしらず、経験者がこんなミスをするとは (a newcomer would pass, but an experienced person (of all people) making such a mistake — first admitting “a newcomer's okay,” then criticizing “an experienced person's not”). Its latter clause mostly carries negation, criticism, contrast (highlighting the present's unacceptability). 「〜は別として」 = ～ aside (shelving some topic for now, more neutral, without criticism): it just neutrally “shelves ～ for now, talking of something else,” without the “exception okay／present not” contrast-negation: 費用は別として、まずは計画を立てよう (cost aside, let's first make a plan — shelving “cost” for now, talking of something else, neutral). Difference: 「ならいざしらず」 = set an exception then turn to negate the present (with contrast, criticism, the latter often a negation); 「は別として」 = neutrally shelve some topic (without criticism). Test: to say with contrast, criticism “(that) another matter, but (this present) won't do／is different” → ならいざしらず; to just neutrally “～ aside, talking of something else” → は別として. So the critical “a newcomer's okay, but a veteran (of all people) making a mistake” uses 「新人ならいざしらず,」 the neutral “cost aside, let's make a plan” uses 「費用は別として.」

🖊️ Practice Questions (5)

Q1. 「新入社員___、課長がこんなミスをするとは。」（if it were a new employee, fine, but...）

(A) ならいざしらず　(B) だからこそ　(C) はもとより　(D) に限って

Q2. 「ならいざしらず」の前項の役割は?

(A) An understandable extreme case, used to contrast with the following clause

(B) A conclusion

(C) A command

(D) Pure time

Q3. 「子供ならいざしらず大人が」の意味は?

(A) If it were a child it'd be excusable, but an adult...

(B) Both children and adults are fine

(C) Only children are allowed

(D) Neither adults nor children are allowed (no contrast)

Q4. 「ならいざしらず」の語感は?

(A) If it were ~ that would be another matter (contrasting with the following clause)

(B) Because ~, therefore

(C) Even if ~

(D) Along with ~

Q5. 接法が正しいのは?

(A) 学生ならいざしらず、社会人が…。　(B) 学生をならいざしらず。

(C) 学生だならいざしらず。　(D) 学生ならいざしらずを。

Answer Explanations

1. (A) ならいざしらず ── If it were a new employee, fine.

2. (A) ── An understandable case contrasting with the following clause.

3. (A) ── Excusable for a child, but an adult...

4. (A) ── If it were ~ that would be another matter.

5. (A) ── 「学生ならいざしらず」 is correct.