Meaning & Usage
✨ Basic Meaning
It should be the case that; It is expected that; It must be.
🎯 Primary Function
To express a strong conviction, expectation, or logical certainty based on evidence or knowledge.
📋 Grammar Structure
動詞 (Plain Form) + はずだ
い形容詞 (Plain Form) + はずだ
な形容詞語幹 (Stem) + な + はずだ
プレーンフォームの否定形 (Plain Negative Form) + はずだ
🎭 Usage Contexts
Formal Situations
Used but often softened to はずです (hazu desu) or はずでございます (hazu de gozaimasu).
Informal Situations
Commonly used in plain form (はずだ / はずだよ / はずなの).
Written Language
Used in formal reports, essays, and news reports to present conclusions based on facts.
Spoken Language
Very common for expressing certainty in daily conversations.
💡 Common Applications
Expressing Strong Expectation/Assumption
Used when you are almost certain about something based on prior information or logical deduction.
Example: 彼は今日、出張から帰ってくるはずだ。 (Kare wa kyō, shucchō kara kaette kuru hazu da.)
Stating a Logical Conclusion
Used to draw a conclusion based on a premise (a reading, an observation, a fact).
Example: 説明書を読んだから、使い方はわかるはずだ。 (Setsumeisho o yonda kara, tsukaikata wa wakaru hazu da.)
Expressing Surprise/Disagreement (with が/のに)
Often used with negative forms (はずがない) to express “it cannot possibly be” or “it shouldn’t be.” This implies a contradiction between an expectation and reality.
Example: 日本語を勉強したのに、話せないはずがない。 (Nihongo o benkyō shita noni, hanasenai hazu ga nai.)
Frequency
High
Difficulty
N4 / N3 (Intermediate)
Tag:
Example Sentences
Example #1
彼は地図を送ったので、もう着いているはずだ。
Furigana: かれはちずをおくったので、もうついているはずだ。
Romaji: Kare wa chizu o okutta node, mō tsuite iru hazu da.
English: He should be here by now because I sent him the map.
Example #2
図書館は今日午後7時まで開いているはずだ。
Furigana: としょかんはきょうごごしちじまであいているはずだ。
Romaji: Toshokan wa kyō gogo shichiji made aite iru hazu da.
English: The library should be open until 7 PM today.
Example #3
こんなに勉強したんだから、試験は難しくないはずだ。
Furigana: こんなにべんきょうしたんだから、しけんはむずかしくないはずだ。
Romaji: Konna ni benkyō shita n dakara, shiken wa muzukashiku nai hazu da.
English: If you studied this much, the exam shouldn’t be difficult.
Example #4
彼女はとても慎重な人なので、そんな簡単な間違いはしないはずだ。
Furigana: かのじょはとてもしんちょうなひとなので、そんなかんたんなまちがいはしないはずだ。
Romaji: Kanojo wa totemo shinchō na hito nano de, sonna kantan na machigai wa shinai hazu da.
English: She is a very careful person, so she shouldn’t make such a simple mistake.
Example #5
電車は5番線に到着するはずだ。
Furigana: でんしゃはごばんせんにとうちゃくするはずだ。
Romaji: Densha wa goban-sen ni tōchaku suru hazu da.
English: The train is supposed to arrive at Platform 5.
Example #6
会議の場所は静かなはずだ。
Furigana: かいぎのばしょはしずかなはずだ。
Romaji: Kaigi no basho wa shizuka na hazu da.
English: The meeting place is supposed to be quiet.
Example #7
このケーキはとても人気があるので、美味しいはずだ。
Furigana: このケーキはとてもにんきがあるので、おいしいはずだ。
Romaji: Kono kēki wa totemo ninki ga aru node, oishii hazu da.
English: This cake is really popular, so it must be delicious.
Example #8
私の財布はこのカバンの中にあるはずだ。
Furigana: わたしのはずだ。
Romaji: Watashi no saifu wa kono kaban no naka ni aru hazu da.
English: My wallet should be in this bag.
Example #9
スケジュールによると、来月プロジェクトが終わるはずだ。
Furigana: スケジュールによると、らいげつプロジェクトがおわるはずだ。
Romaji: Sukejūru ni yoru to, raigetsu purojekuto ga owaru hazu da.
English: According to the schedule, we are supposed to finish the project next month.
Example #10
鍵は見つけにくいわけではないはずだ。
Furigana: かぎはみつけにくいわけではないはずだ。
Romaji: Kagi wa mitsuke nikui wake de wa nai hazu da.
English: The keys shouldn’t be difficult to find.
Notes & Nuances
📌 Important Points
Expresses High Certainty (Based on Logic)
はずだ conveys a high degree of certainty (around 80-99%). It implies the speaker has solid reasons or proof for their assertion.
Example: 先生に確認したから、間違いないはずだ。(Sensei ni kakunin shita kara, machigai nai hazu da.)
Negative Form: はずがない (Logically Impossible)
The negative form はずがない or はずはない emphasizes that something is logically impossible, meaning “it cannot possibly be.”
Example: こんな難しいテストは、合格者が少ないはずがない。 (Konna muzukashii tesuto wa, gōkaku-sha ga sukunai hazu ga nai.)
Noun Connector: Noun + の + はずだ
When the preceding element is a Noun, the particle の is required (Noun + の + はずだ). When the Noun is part of a Noun Phrase (Noun + である), の is not strictly necessary.
Example: 彼は日本人なのだから、漢字が読めるはずだ。 (Kare wa Nihonjin nano da kara, kanji ga yomeru hazu da.)
⚠️ Common Mistakes
❌ 雨が降りますはずだ。 (Ame ga furimasu hazu da.)
✅ Use the plain form of the preceding word.
Learners sometimes incorrectly use the polite form (ます form) before はずだ. It must always be the plain form (dictionary form, ta form, nai form).
❌ このかぎはわたしはずだ。 (Kono kagi wa watashi hazu da.)
✅ Use の before はずだ when the preceding word is a Noun.
Failing to include the connecting particle の after a Noun is a common error.
❌ あの人は忙しいらしいだ。 (Ano hito wa isogashii rashii da.) [Should be らしい or 忙しいはずだ]
✅ Understand the difference from らしい (rashii).
While both express assumption, はずだ is based on logic/evidence, while らしい is based on hearsay or superficial appearance. Do not interchange them.
🏛️ Cultural Context
Politeness Level: Medium. Using はずです is polite, but the expression itself is inherently assertive. Contextual politeness is achieved through the ending (です/ます).
Social Situations: Appropriate for making predictions, confirming schedules, or stating logical deductions among equals or to subordinates. When speaking to superiors, combine with humble or honorific verbs before はずです.
Regional Variations: The core grammar is standard, but the copula だ may be dropped or replaced with regional variations (e.g., や in Kansai).
🔍 Subtle Differences
はずだ (hazu da) vs. だろう (darō)
はずだ relies on objective facts, data, or explicit rules for its certainty. だろう expresses a subjective guess or prediction without necessarily strong evidence (lower certainty).
When to use: Use はずだ when you have concrete information (a schedule, a rule, a witness). Use だろう for a general prediction or speculation.
はずだ (hazu da) vs. に違いない (ni chigai nai)
はずだ is a strong logical conclusion. に違いない means “no mistake,” implying absolute conviction, often based on emotion or immediate observation (slightly stronger certainty).
When to use: Use はずだ when you want to sound deductive. Use に違いない when you want to sound emphatic or convinced without a doubt.
はずだ (hazu da) vs. らしい (rashii)
はずだ is based on internal logic/evidence. らしい is based on external hearsay, rumors, or superficial appearance. らしい is a weaker assertion.
When to use: Use はずだ when you know the fact. Use らしい when you’ve just heard about it from someone else.
📝 Conjugation Notes
はず is a nominalized form, which is why it requires の when following a Noun and な when following a Na-adjective stem. The suffix だ (or です) conjugates the entire phrase for tense and politeness. For example, Past tense: だったはずだ (datta hazu da).
🔊 Pronunciation Tips
The stress is usually on the second syllable of はず (ha-ZU). Ensure the preceding plain form is clearly pronounced before connecting to はずだ.
🧠 Memory Tips
Think of はず as ‘logic’ or ‘reason’. If something is logical or reasonable, it *should* be true. Connect it to the English phrase ‘It’s reasonable to assume that…’
Other Grammar
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