目錄
Japanese 「AはBです」 is used to introduce a topic first and then provide information about its identity, name, or classification. Textbooks usually translate it directly as “A is B,” so when learners see 「これは本です」, they may simply remember “This is a book” without noticing that 「これ」 is first brought up as the topic, while 「本です」 then adds the explanation. The difference may seem minor, but it comes up repeatedly later in self-introductions, location checks, and comparisons between 「は／が」. Understanding how the first and second halves of the sentence divide their roles is more practical than constantly matching the Japanese sentence to a Chinese translation.
What does Japanese 「AはBです」 mean? Start with “topic + explanation”
Japanese 「AはBです」 is often understood as “A is B.” This works as an introductory explanation, but it should not stop there. 「は」 is not simply an equals sign; it is a topic particle that marks A and indicates, “What we are going to talk about is A.” B then provides the explanation about A.
This is why Japanese can say 「田中さんは先生です」「ここは駅です」「今日は休みです」. A does not have to be a person. It can also be a place, time, object, or abstract topic. The pattern looks simple, but it is actually one of the most important “topic → explanation” frameworks in Japanese sentences.
Basic structure of Japanese 「AはBです」: noun attachment and how 「です」 works
The basic form of Japanese 「AはBです」 is 「noun A＋は＋noun B＋です」. A is the topic, B is the explanation or judgment, and the sentence-final 「です」 makes the sentence polite. An adjective can also be used to form 「Aはadjectiveです」, but this article focuses on noun sentences first so that the basic framework is firmly established.
| Position | Function | Example | Explanation |
| A | Topic | これは | The object that will be discussed |
| は | Topic particle | は | Marks the topic; it is not an equals sign |
| B | Explanatory content | 本 | A judgment or classification of the topic |
| です | Polite sentence ending | です | Completes the sentence and makes it polite |
Usage ① of 「AはBです」｜Expressing identity, occupation, or classification
「AはBです」 is most commonly used to describe identity, occupation, or classification. The sentence places A as the topic and then uses B to explain what category it belongs to. Beginners may be tempted to map the pattern directly to Chinese “是,” but Japanese places more emphasis on the idea that “A is what we are talking about now.” It is used in self-introductions, when introducing friends, and when explaining what type of object something is.
- Example: 田中さんは先生です。
Kana: たなかさんは せんせいです。
Translation: Mr. Tanaka is a teacher.
「田中さんは」 introduces the topic first, and 「先生です」 then explains his identity. - Example: これは日本語の教科書です。
Kana: これは にほんごの きょうかしょです。
Translation: This is a Japanese textbook.
「これ」 refers to the object in front of the speaker, while 「日本語の教科書」 explains its classification. - Example: 東京は日本の首都です。
Kana: とうきょうは にほんの しゅとです。
Translation: Tokyo is the capital of Japan.
This sentence makes Tokyo the topic and then provides its status in the second half.
Usage ② of 「AはBです」｜Explaining places, time, or status
「AはBです」 is not limited to introducing people. It can also be used to explain places, dates, or the status of activities. Expressions such as 「ここは駅です」 and 「今日は休みです」 are very common. In these cases, B is not an occupation or identity but information about A’s location, nature, or schedule. It is a highly practical basic pattern in both travel Japanese and everyday Japanese.
- Example: ここは京都駅です。
Kana: ここは きょうとえきです。
Translation: This is Kyoto Station.
「ここは」 introduces the location as the topic, and the second half explains what place it is. - Example: 今日は日曜日です。
Kana: きょうは にちようびです。
Translation: Today is Sunday.
This sentence makes 「今日」 the topic and explains it by stating the day of the week. - Example: 次の予定は会議です。
Kana: つぎの よていは かいぎです。
Translation: The next item on the schedule is a meeting.
「次の予定」 is the topic, and 「会議」 is the content of that schedule.
Usage ③ of 「AはBです」｜Expressing contrast or limiting the topic
「は」 can also carry a sense of contrast or topic limitation. The surface form is still 「AはBです」, but the nuance may be closer to “As for A, it is B.” When introducing several people or comparing several places, 「は」 makes each A stand out. This is also one of the major differences between 「は」 and 「が」: 「は」 is often used to manage the topic rather than simply mark the grammatical subject.
- Example: 田中さんは先生です。山田さんは学生です。
Kana: たなかさんは せんせいです。やまださんは がくせいです。
Translation: Mr. Tanaka is a teacher, and Mr. Yamada is a student.
The two instances of 「は」 bring the two people up separately for comparison, with a nuance like “as for Tanaka” and “as for Yamada.” - Example: この店は有名です。あの店は静かです。
Kana: このみせは ゆうめいです。あのみせは しずかです。
Translation: This shop is famous, and that shop is quiet.
「は」 makes each shop its own topic, making it easier to compare their characteristics. - Example: 朝はパンです。夜はご飯です。
Kana: あさは パンです。よるは ごはんです。
Translation: I have bread in the morning and rice at night.
This sentence uses 「朝は／夜は」 to limit the topic by time. Even with 「食べる」 omitted, the sentence sounds natural.
What is the difference between 「AはBです」 and 「AがBです」?
The biggest difference between 「AはBです」 and 「AがBです」 is that 「は」 introduces a topic, while 「が」 marks focus or new information. For beginners, understanding 「は」 as “as for A” is more accurate than treating it as an equals sign. When answering “which one is B?”, Japanese often uses 「が」. When explaining “what A is,” 「は」 is often used.
| Comparison | AはBです | AがBです | Common mistake |
| Core function | Introduces a topic | Marks focus | Translating both simply as “is” |
| Common situation | Explaining A | Identifying which one is B | Using は in every sentence |
| Nuance | As for A | It is A | Ignoring the focus of the question |
| Example | これは本です | これが本です | Confusing the topic with the answer focus |
▌Why does 「これは本です」 use 「は」? Explaining an established topic
❌ Unnatural interpretation: これは本です＝これ and 本 are completely identical.
✅ Correct interpretation: これは本です.
This sentence has the structure “As for this, it is a book,” with the focus on classifying and explaining the object in front of the speaker.
▌Why is 「が」 used when answering “which one”?
❌ Mismatched context: どれが本ですか。これは本です.
✅ Natural: どれが本ですか。これが本です.
The question is asking “which one,” so using 「が」 in the answer is more natural because it marks the answer itself as the focus.
▌When introducing two people side by side, use 「は」 to create contrast
❌ Less natural: 田中さんが先生です。山田さんが学生です.
✅ Natural: 田中さんは先生です。山田さんは学生です.
If the purpose is to introduce the two people separately, using 「は」 to establish each person as a topic is more natural.
Practical Japanese 「AはBです」 for travel and self-introductions: 3 common situations
In Japanese travel situations and self-introductions, 「AはBです」 is one of the most frequently used basic patterns. It appears at hotels, stations, restaurants, and in classroom self-introductions. Its advantage is that it is simple, stable, and highly reusable. As long as you know that A is the topic and B is the explanation, you can quickly build sentences with it.
▌Situation ①｜Checking a location at a station
A：ここは京都駅ですか。
ここは きょうとえきですか。
Is this Kyoto Station?
B：はい、ここは京都駅です。
はい、ここは きょうとえきです。
Yes, this is Kyoto Station.
📌 Grammar Point: 「ここは」 brings up the location as the topic, and 「京都駅です」 explains the name of the place.
▌Situation ②｜Introducing yourself in class
A：田中さんは学生ですか。
たなかさんは がくせいですか。
Is Mr. Tanaka a student?
B：はい、学生です。専攻は日本文学です。
はい、がくせいです。せんこうは にほんぶんがくです。
Yes, he is a student. His major is Japanese literature.
📌 Grammar Point: In the answer, an already established topic can be omitted. The second sentence uses 「専攻は」 to introduce a new topic.
▌Situation ③｜Introducing a restaurant’s specialty
A：この店は何のお店ですか。
このみせは なんの おみせですか。
What kind of restaurant is this?
B：ここはラーメンの店です。夜はとても混みます。
ここは ラーメンの みせです。よるは とても こみます。
This is a ramen restaurant. It gets very crowded at night.
📌 Grammar Point: 「ここは」 explains the type of restaurant, while 「夜は」 introduces time as another topic.
Cultural Notes:
- Japanese places a strong emphasis on topic management. Even the most basic pattern 「AはBです」 already reflects the logic of “first bringing up A as the thing to talk about.”
- In self-introductions, there is no need to repeat a person’s name in every sentence. Once the topic is clear, Japanese often omits it, which actually makes the sentence sound more natural.
- In travel Japanese, 「ここは〜です」「今日は〜です」「次は〜です」 are highly practical. These patterns make it easy to quickly confirm locations, times, and schedules.
How does Japanese 「AはBです」 compare with Korean 「A은/는 B입니다」?
◆ Similar grammar: Korean 「A은/는 B입니다」
Korean also has the topic particles 「은/는」, which can form the basic pattern 「A은/는 B입니다」. It is very similar to Japanese 「AはBです」 because both first introduce a topic and then explain it. However, Korean chooses between 「은／는」 depending on whether the preceding noun has a final consonant, while Japanese always uses 「は」.
- Example: 여기는 교토역입니다.
Romanization: yeo-gi-neun gyo-to-yeo-gim-ni-da
Translation: This is Kyoto Station.
「여기는」 corresponds to Japanese 「ここは」, and both treat the location as the topic. - Example: 다나카 씨는 선생님입니다.
Romanization: da-na-ka ssi-neun seon-saeng-ni-mim-ni-da
Translation: Mr. Tanaka is a teacher.
「씨는」 introduces the person as the topic, and the second half explains the person’s identity. - Example: 오늘은 일요일입니다.
Romanization: o-neu-reun i-ryo-i-rim-ni-da
Translation: Today is Sunday.
「오늘은」 and Japanese 「今日は」 can both be used to talk about a date or time as the topic.
◆ Core difference from 「AはBです」:
Japanese 「は」 does not change according to the form of the preceding word, while Korean 「은／는」 changes depending on whether the noun has a final consonant. Neither is simply an equals sign; both are topic markers. Understanding them as “As for A, B is the explanation about it” is more reliable than memorizing them merely as “is.”
Japanese 「AはBです」 can be divided into two parts: 「Aは」 establishes what is currently being discussed, and 「Bです」 then adds the explanation. In sentences such as 「これは本です」 and 「今日は日曜日です」, first identify whether the first half is talking about an object or a date, and the information in the second half becomes easier to connect. Later, when you encounter 「ではありません」, 「Aは形容詞です」, or the difference between 「は／が」, you can continue breaking sentences down in the same way rather than memorizing an entirely separate set of rules.
FAQs
Japanese 「AはBです」 means “As for A, it is B.” It is often translated as “A is B,” but its core structure is to introduce the topic first and then explain it.
No. 「は」 is a topic particle, not “is.” The element that makes the sentence a polite judgment statement is the final 「です」.
「これは本です」 explains that “this” is a book. 「これが本です」 is often used to answer a question such as “Which one is the book?”, marking 「これ」 as the focus.
Yes. It is commonly used to introduce identity, occupation, major, nationality, and similar information, as in 「田中さんは学生です」 and 「専攻は日本文学です」.
Start with three types of words: people, places, and time. For people, use examples such as 「田中さんは先生です」; for places, 「ここは駅です」; and for time, 「今日は日曜日です」.