How to Deal With Humidity in a Japanese Apartment: 9 Local Tips

If you’ve recently moved to Japan, there’s a good chance you’ve already noticed one thing:

Japan can be incredibly humid.

And it’s not just an outdoor problem.

During the rainy season and summer, moisture can build up inside Japanese apartments too. Closets start to smell musty. Laundry takes forever to dry. Windows collect condensation. And if you ignore it long enough, mold can appear in places you didn’t even think to check.

The good news is that Japanese homes — and Japanese stores — have plenty of ways to deal with it.

Here are the things I would actually recommend if you were moving into a Japanese apartment today.

Why Are Japanese Apartments So Humid?

Japan has a hot and humid summer climate in most major cities, with especially uncomfortable conditions during the rainy season and summer months.

Inside an apartment, moisture tends to become more noticeable when:

• Your room gets little sunlight
• Airflow is poor
• You dry laundry indoors
• Furniture sits directly against walls
• Closets stay closed for long periods
• The bathroom stays damp

Humidity itself isn’t necessarily the biggest problem.

The real problem is what happens when warm, damp air stays trapped in the same place for too long.

That’s when you start getting musty smells — and eventually, mold.

1. Learn the “Dry” Mode on Your Air Conditioner

One of the first things I would show any foreign friend moving to Japan is the 除湿 (joshitsu) or ドライ (dry) button on the air conditioner remote.

It’s the dehumidifying mode.

A lot of people only use regular cooling mode, but many Japanese air conditioners have a dedicated setting designed to reduce moisture.

If your apartment feels humid but not particularly hot, try Dry mode first.

If it’s humid and extremely hot, regular cooling may make more sense.

2. Buy a Proper Dehumidifier If Your Apartment Is Really Damp

For a mildly humid room, air conditioning may be enough.

For a genuinely damp apartment, I would consider buying an actual dehumidifier.

In Japanese, search for:

除湿機 (joshitsuki)

You’ll find them at places like:

• Yodobashi Camera
• Bic Camera
• Amazon Japan
• Rakuten
• Home appliance stores

The main thing to check is the recommended room size.

A tiny unit designed for a closet won’t solve humidity problems across an entire apartment.

3. Use Japanese Moisture Absorber Boxes

This is one of those very Japanese household products that newcomers often don’t know exists.

Walk into a Japanese drugstore or home center and you’ll probably find plastic containers filled with moisture-absorbing material.

They’re commonly used in:

• Closets
• Shoe cabinets
• Storage spaces
• Under sinks
• Small enclosed areas

You might see words like:

除湿剤
湿気取り

Think of them as passive moisture traps.

They’re inexpensive and don’t require electricity.

For a tiny closet? Excellent.

For your whole apartment? Not enough.

4. Don’t Ignore Your Closets

Closets are one of the easiest places for humidity problems to hide.

They’re:

• Dark
• Enclosed
• Often packed with clothes
• Rarely ventilated

And yes — mold can grow directly on clothes.

A few simple habits help:

• Don’t pack clothes too tightly
• Occasionally leave closet doors open
• Use moisture absorbers
• Avoid putting damp clothes away
• Allow air to circulate

If your apartment is especially humid, check behind stored bags and boxes too.

5. Keep Air Moving

Humidity becomes much more annoying when air stays still.

A cheap fan or circulator can make a surprisingly big difference.

In Japan, you’ll often see:

サーキュレーター (circulator)

These are small fans designed mainly to move air around a room rather than just blow directly at you.

Use one to:

• Circulate air-conditioning
• Dry laundry
• Move air through closets
• Reduce stagnant damp areas

If you’re drying clothes indoors, pointing a circulator toward them can also significantly improve drying time.

6. Use Your Bathroom Ventilation Fan

Japanese bathrooms often have an exhaust fan.

Use it.

Especially after taking a shower.

A wet Japanese bathroom can stay humid for a long time if you shut the door and forget about it.

Keep the ventilation fan running and let the bathroom dry properly.

7. Be Careful When Drying Laundry Indoors

Rainy season creates an annoying cycle:

It rains.

You can’t dry your clothes outside.

So you dry them inside.

Which increases indoor humidity.

If you regularly dry clothes indoors, combine it with:

• Air conditioning
• Dry mode
• A dehumidifier
• A circulator

Many Japanese dehumidifiers also have 衣類乾燥, or laundry-drying modes.

This feature can genuinely make life easier during rainy season.

8. Check Behind Furniture

This is the humidity problem nobody notices until moving day.

Beds. Bookshelves. Washing machines. Storage cabinets.

Furniture positioned directly against an exterior wall can create poorly ventilated pockets where moisture accumulates.

Leave a small gap between large furniture and walls when possible.

And every few months?

Take a look.

Your future self will thank you.

9. Deal With Mold Early

If you see mold, don’t wait several months hoping it will magically disappear.

Japan has a huge selection of anti-mold cleaning products.

At a Japanese drugstore, look for products labeled:

カビ取り

which essentially means mold remover.

Bathrooms are the most obvious place, but also inspect:

• Window frames
• Closet walls
• Behind furniture
• Washing-machine areas
• Tatami rooms
• Shoe cabinets

Persistent mold can be a sign of a larger moisture or building issue, so if the problem keeps returning despite proper ventilation and dehumidification, contact your landlord or property manager.

What I Would Buy First

If I were moving into a Japanese apartment today, I would start with these four things:

1. Hygrometer

First, actually know how humid your room is.

2. Moisture Absorbers

Use these inside closets and shoe cabinets.

3. Circulator

Useful for humidity, laundry, and air-conditioning efficiency.

4. Dehumidifier

If your apartment consistently feels damp, this is the upgrade that makes the biggest difference.

A Simple Humidity Setup by Budget

Under ¥1,000

Buy:

• Moisture absorber boxes
• Basic hygrometer

Best for small closets and mild humidity.

Around ¥5,000

Add:

• Circulator
• More moisture absorbers

Best for small apartments and indoor laundry.

¥15,000–¥30,000+

Consider:

• A proper electric dehumidifier

Best for very humid apartments, rainy season, frequent indoor laundry, or mold concerns.

The Most Important Thing to Remember

Humidity in Japan isn’t something you need to be terrified of.

But it is something you need to manage.

The easiest routine is:

Measure humidity.
Keep air moving.
Use your air conditioner intelligently.
Protect closets.
Deal with moisture before mold appears.

Once those habits become normal, Japanese summer becomes much easier to handle.

And yes — after living here long enough, you may eventually find yourself getting strangely excited about a really good dehumidifier.

That’s when you know Japan has changed you.

Quick Checklist

• Check your AC’s Dry / 除湿 mode
• Buy moisture absorbers for closets
• Get a hygrometer
• Ventilate the bathroom
• Leave space behind furniture
• Use a circulator for indoor laundry
• Check closets and window frames for mold
• Consider a dehumidifier if humidity stays high