What do people get wrong about using a microwave oven?

This answer is a draft. It stays unpublished until legal review and source verification are complete.

Microwave ovens are in kitchens all over the world. What is unusual in Japan is that the number of accidents, and their causes, are recorded by public bodies. Those records show where the risk really lies.

Accidents in numbers

• NITE (National Institute of Technology and Evaluation): in the five fiscal years 2014–2018, 157 microwave-oven accidents were notified. Compared with other products, the share of accidents caused by user misuse or carelessness is described as high.
• National Consumer Affairs Center of Japan: from April 2020 to December 2025 (five years and nine months), 521 consumer consultations about microwave ovens. It issued a fresh warning in March 2026.

[Verify] The figures are based on a NITE press release (27 February 2020) and a National Consumer Affairs Center announcement (25 March 2026). Check the original text before publication.

Misunderstanding 1｜It heats evenly

A microwave heats by agitating the water in the food, so the wetter parts heat faster. Stir part-way through, or change the position of the food — that alone reduces uneven heating.

Misunderstanding 2｜Eggs can go in as they are

Both raw eggs and boiled eggs burst when heated, because the pressure inside rises. NITE has published a warning poster about it. Moreover, an egg that did not burst inside the oven can burst after you take it out, so if you have heated one by mistake, leave it alone until it has cooled down.

Misunderstanding 3｜The tighter the cling film, the better

Sealing tightly can raise the pressure inside. Lay the film on loosely — that is the basic rule.

Misunderstanding 4｜For a small amount, just shorten the time

Heating something with very little moisture can cause it to catch fire. The smaller the amount, the more care is needed. NITE has also warned about accidents from "lazy cooking" (ずぼら調理, *zubora chōri* — careless shortcut cooking) (September 2024).

Misunderstanding 5｜Reheating doesn't need to be thorough

Under-heated food can cause food poisoning. The Ministry of Health, Labour and Welfare's guide figure for preventing food poisoning is a core temperature of 75°C for at least one minute.

Misunderstanding 6｜Any container will do

Metal and some plastics cannot be used. Always check the markings on the container (in Japan, look for 電子レンジ対応 or 電子レンジ可, meaning "microwave-safe").

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Sources

• National Institute of Technology and Evaluation (NITE) [独立行政法人 製品評価技術基盤機構], "157 accidents in 5 years: accidents involving microwave ovens" [5年で157件、電子レンジで発生する事故] (27 February 2020)

https://www.nite.go.jp/jiko/chuikanki/press/2019fy/prs200227.html

• NITE warning poster, "Microwave ovens 6. Bursting raw eggs" [電子レンジ 6. 生卵の破裂]

https://www.nite.go.jp/jiko/chuikanki/poster/kaden/20022701.html

• National Consumer Affairs Center of Japan [独立行政法人 国民生活センター], "Prevent microwave-oven accidents! Time to re-check how you use it" [電子レンジによる事故を防止！使い方を再チェックしませんか？] (25 March 2026)

https://www.kokusen.go.jp/news/data/n-20260325_1.html

⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.

About this article

What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.

This is general information. Results vary from person to person and depend on your own conditions and surroundings.

Please decide for yourself, using your own judgement, whether any of this suits your situation. We cannot accept responsibility for any damage, loss or injury arising from following this article.

Some ingredients need thorough cooking. Eat raw only foods that are sold for raw consumption. If you have allergies, check the ingredients.

Sources

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