What Is Changing
From April 24, 2026, the use of mobile batteries (portable lithium-ion battery packs) on aircraft is completely banned in Japan. The Ministry of Land, Infrastructure, Transport and Tourism (MLIT) has revised the Dangerous Goods Transport Regulations under the Civil Aeronautics Act to implement this change.
Previously, mobile batteries could be carried on board and used during flights, although they were prohibited in checked baggage. Under the new rules, carry-on is still permitted, but any use (charging) during the flight is banned.
Key Changes
| Item | Before (until 4/23) | After (4/24 onward) |
|---|---|---|
| Carry-on | OK (with conditions) | OK (with conditions) |
| Use on board (battery to device) | OK | Banned |
| Use on board (device to battery) | OK | Banned |
| Checked baggage | Banned | Banned (no change) |
Carry-On Rules in Detail
| Condition | Rule |
|---|---|
| Quantity limit | 2 units per person |
| Capacity limit | 160Wh or less (approx. 43,000mAh) |
| Over 100Wh to 160Wh | Advance notification to airline may be required |
| Over 160Wh | Not allowed on board |
| Checked baggage | Completely banned (regardless of capacity) |
How to Calculate Wh
If your mobile battery shows capacity in mAh, convert using:
Wh = mAh x V (voltage) / 1,000
Standard lithium-ion voltage is 3.7V, so a 20,000mAh battery equals 20,000 x 3.7 / 1,000 = 74Wh (carry-on permitted).
Penalties for Violations
Using a mobile battery on board may result in fines of up to ¥500,000 under Article 150 of the Civil Aeronautics Act.
Additional consequences may include:
- Captain's order to cease use
- Handover to police upon landing if the order is ignored
- Placement on the airline's blacklist
Placing mobile batteries in checked baggage also remains a violation of the Civil Aeronautics Act.
Why Is Use Being Banned?
Lithium-ion batteries in mobile chargers carry the following risks:
- Thermal runaway: External impact, overcharging, or internal short circuits can cause rapid heating, fire, or explosion
- Toxic gas emission: Thermal runaway produces toxic gases such as hydrogen fluoride
- Confined space danger: Fire suppression and ventilation are extremely difficult in an aircraft cabin
In-flight fire incidents attributed to mobile batteries have been reported worldwide, and the International Civil Aviation Organization (ICAO) has indicated a move toward stricter regulation.
Pre-Golden Week Travel Checklist
Since enforcement begins just before Golden Week (April 26 to May 6), travelers should prepare in advance.
Before Departure
- Ensure mobile batteries are in your carry-on luggage (not checked bags)
- Verify each battery is 160Wh or less (check the label)
- Confirm you are carrying no more than 2 batteries
- Notify the airline in advance if any battery exceeds 100Wh
- Double-check that no batteries are in your checked luggage
- Understand that battery use is prohibited during the flight
- Charge your devices fully before boarding (use airport charging stations)
Alternatives During Flight
- Seat USB/outlets: Some airlines and aircraft offer in-seat power. Check your airline's website in advance.
- Pre-boarding charging: Make full use of airport charging spots and lounges before your flight.
Frequently Asked Questions
Q1. Are smartphones and laptops also restricted?
No. This regulation targets the "use" of mobile batteries (portable chargers). Smartphones, laptops, tablets, and other electronic devices may still be used on board as before. However, the 160Wh limit applies to built-in batteries as well.
Q2. Can I charge my phone with a mobile battery if it dies during the flight?
No. From April 24, all use of mobile batteries during flight is prohibited — whether charging a device from the battery or charging the battery from a device.
Q3. Does this apply to international flights?
The regulation applies to all flights departing from or arriving in Japan, both domestic and international. However, flights operated by foreign airlines may be subject to the regulations of their home country.
Q4. Are e-cigarette batteries covered?
Lithium-ion batteries in e-cigarettes and heated tobacco devices are also banned from checked baggage. They may be carried on board, but their use (smoking) has always been prohibited in-flight.
Q5. What if my battery has no capacity label?
Batteries without capacity markings cannot be verified for safety, and some airlines may refuse to allow them on board. Check with the manufacturer before traveling, or use a battery with clear capacity labeling.
Summary
Three key points to remember:
- All in-flight use is banned — no charging in either direction
- Carry-on: 2 units max, 160Wh or less — checked baggage remains prohibited
- Violations carry fines up to ¥500,000 — enforceable under the Civil Aeronautics Act
If you are traveling during Golden Week, check your battery capacity and count before departure, and fully charge your devices before boarding. Follow the rules and enjoy a safe flight.
