anzen-vs-kiken

How do you say “safe” and “dangerous” in Japanese? 安全 (anzen) and 危険 (kiken) are essential vocabulary for travel, daily conversation, and understanding Japanese signs and warnings. They are na-adjectives (な形容詞), which means they behave differently from i-adjectives — and knowing the grammar will help you use them correctly in any situation.

Yuka

Hey Rei, what’s the best way to remember the difference between anzen and kiken?

Rei

The best trick is to associate each word with a strong image or situation. By the end of this article you’ll have one for each — promise!

At a Glance

Both words are na-adjectives (also called adjectival nouns). This means they need な (na) when modifying a noun directly: 安全な場所 (a safe place), 危険な場所 (a dangerous place).

What Does 安全 (Anzen) Mean?

安全 (あんぜん) means safe or safety — free from danger, harm, or risk. It is used both as an adjective (“this is safe”) and as a noun (“safety first”).

Kanji breakdown: 安 (an) = “peace / ease” + 全 (zen) = “complete / whole.” Together: “complete peace” = safety.

Example 1

この場所は安全だよ。
Kono basho wa anzen da yo.
This place is safe.

Example 2

日本は安全な国です。
Nihon wa anzen na kuni desu.
Japan is a safe country.

Example 3

安全運転でお願いします。
Anzen unten de onegai shimasu.
Please drive safely.

Example 4

ここは泳いでも安全だよ。
Koko wa oyoide mo anzen da yo.
It is safe to swim here.

What Does 危険 (Kiken) Mean?

危険 (きけん) means dangerous or danger — involving risk of harm, injury, or threat. Like 安全, it functions as both an adjective and a noun.

Kanji breakdown: 危 (ki) = “dangerous / precarious” + 険 (ken) = “steep / risky.” Together: “risky and precarious” = danger.

Example 1

この場所は危険だよ。
Kono basho wa kiken da yo.
This place is dangerous.

Example 2

女性が夜一人で歩くのは危険です。
Josei ga yoru hitori de aruku no wa kiken desu.
It is dangerous for a woman to walk alone at night.

Example 3

ここは泳いだら危険だよ。
Koko wa oyoidara kiken da yo.
It is dangerous to swim here.

Example 4

その薬は飲みすぎると危険です。
Sono kusuri wa nomisugiru to kiken desu.
Taking too much of that medicine is dangerous.

Anzen vs. Kiken: Side-by-Side Comparison

Grammar Deep Dive: Na-Adjective Usage

Both 安全 and 危険 are na-adjectives (な形容詞). Here is how to use them in the most common patterns:

Important note for English speakers: Unlike English “safe” and “dangerous” which directly modify nouns (a safe road, a dangerous road), Japanese na-adjectives need な before the noun. Do not skip the な:

Correct: 安全な場所 (a safe place)
Incorrect: 安全場所 (missing な)

Common Compound Words and Set Phrases

Decision Flowchart: Anzen or Kiken?

Are you describing a level of risk or safety?
              |
              Yes
              |
Is the situation FREE from harm or risk?
       |                   |
      Yes                  No
       |                   |
   安全 (anzen)         Does the situation involve potential harm or danger?
   = safe                  |                   |
                          Yes                  No → Use a different word
                           |
                       危険 (kiken)
                       = dangerous

Adverb tip: To say “safely” (as in “do something safely”), use 安全に (anzen ni). The に (ni) turns na-adjectives into adverbs.
安全に渡ってください。(Anzen ni watatte kudasai.) = Please cross safely.

Quick Quiz: Fill in the Blank

Choose 安全 (anzen) or 危険 (kiken) for each sentence. Answers and explanations are below.

Q1. この川で泳ぐのは＿＿です。流れが速すぎます。
Swimming in this river is _____. The current is too fast.

Q2. 日本の電車は＿＿で時間通りに来ます。
Japanese trains are _____ and come on time.

Q3. ＿＿第一で仕事を進めましょう。
Let’s proceed with work with _____ first.

Q4. あの交差点は見通しが悪くて＿＿だ。
That intersection has poor visibility and is _____.

Q5. 子どもが＿＿に遊べる公園を作りたい。
I want to create a park where children can play _____.

Answers:

A1. 危険 — Fast current = potential harm → この川で泳ぐのは危険です。

A2. 安全 — Trains being safe and reliable → 日本の電車は安全で時間通りに来ます。

A3. 安全 — “Safety first” is the set phrase 安全第一 → 安全第一で仕事を進めましょう。

A4. 危険 — Poor visibility = dangerous → あの交差点は見通しが悪くて危険だ。

A5. 安全 — Adverb form: 安全に (safely) → 子どもが安全に遊べる公園を作りたい。

Summary

Remember: both are na-adjectives, so they always need な before a noun. Once that grammar rule is fixed in your mind, using 安全 and 危険 in natural Japanese sentences becomes straightforward.

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