Caught With Weed at a Japanese Airport: What Happens?

Last verified: 23 October 2026.

What happens if you're caught with weed at a Japanese airport? You face two sets of laws at once. Under the Customs Act, importing cannabis carries up to 10 years in prison and/or a fine of up to ¥30 million [3]. Under the drug law, importing carries 1 to 10 years [7]. The cannabis is confiscated, and a foreign national convicted of a drug offence can be deported [11]. There's no fine-and-go track for tourists and no "small amount" exemption.

Japan's airports are polite, spotless and very good at finding things. That's one form of hospitality you don't want to experience.

The short answer

• Cannabis, THC vapes and THC edibles are all prohibited imports. Japan Customs lists cannabis and other narcotics as goods that can't be brought in [1][2].
• Customs Act penalty: up to 10 years and/or ¥30 million, and an attempt is punished the same way [3].
• Drug-law penalty: 1 to 10 years for importing, and more if it's for profit [7].
• Transit isn't a loophole. A separate Customs Act article covers prohibited goods kept in a bonded area or moved through Japan without entering [3].
• Small amounts get caught. In 2025, Narita alone recorded 28 cases of THC products such as liquids and sweets, 4.7 times the year before [6].
• After arrest, expect up to 23 days in custody before any charge [9].

Two laws, one suitcase

Most articles about Japan only mention the drug law. At the airport, the Customs Act applies too.

Prohibited goods can also be confiscated, and Customs can destroy them or order them shipped back out [2][3].

Japan does have an "administrative notice" procedure that lets some customs offences settle with a payment [3]. We found no official source saying it applies to drug smuggling, so don't count on it.

"It was just a vape pen"

The 2025 figures show why a small amount doesn't mean a small problem.

• Nationwide in 2025, Customs recorded 316 cannabis cases (herb and THC products together), with about 1,531 kg seized. 114 of those cases involved air passengers, 27% more than the year before [5].
• At Narita alone, cases involving THC products (Customs means liquids and sweets containing THC) rose to 28, 4.7 times the year before. Twenty of them involved air passengers [6].
• US-origin THC products at Narita: 13 cases, totalling about 1 kg [6]. That's under 80 grams per case on average: personal-sized products, not a smuggling ring.
• Thailand was the top origin for cannabis herb at Narita, with 9 of 12 cases [6]. Nationwide, Thailand was the second-largest origin after the US [5].

The drug law doesn't care whether the THC came as flower, oil, a gummy or a cartridge. Above Japan's THC residue limits, the product is a narcotic [7][8]. That includes "legal where I bought it" CBD products with too much THC. For the limits, see our free Tokyo summary.

How bags get checked

Japan Customs is open about the tools it uses [4]:

• X-ray and CT scanners for baggage.
• About 130 drug detector dogs nationwide, a programme that started in 1979. They check the baggage of arriving and departing passengers, and mail [4].
• Trace detectors that test swabs from the surface of bags for drugs and explosives [4].
• Electronic declaration gates at Narita, Haneda, Kansai, Chubu, Fukuoka, New Chitose and Naha, linked to Visit Japan Web [4].

Moji Customs says its dogs react to "trace elements" in passengers' personal effects [12]. So a bag that once held cannabis may still get attention.

The declaration matters

Every arriving passenger must make a customs declaration, on paper or through Visit Japan Web [1]. The green channel is only for people carrying nothing dutiable and nothing prohibited or restricted; everyone else uses the red channel [1].

There is no legal way to declare cannabis or THC products and walk out with them [1][2]. If you're unsure whether a CBD product is under the limits, Tokyo Customs says you can't import it, or send it back, until you show it isn't a narcotic. You can choose to abandon it instead [8]. Do that check before you fly, not at the counter.

Changing planes in Japan

Many travellers pass through Narita or Haneda on the way somewhere else. The Customs Act covers that too. Article 109-2 targets prohibited goods that arrive "for purposes other than import" and are stored in a bonded area or moved through Japan as foreign goods, with up to 10 years and/or ¥10 million [3].

Leaving Japan

The dogs work on departing passengers too [4], and exporting cannabis carries the same 1 to 10 years as importing under the drug law [7]. Nobody should be carrying anything out anyway: there's no legal source in Japan for visitors.

If you are stopped

What the UK government tells its citizens [9][10]:

• You can be held without charge for up to 23 days, even for minor offences [9].
• Police must tell you of your right to stay silent and to a lawyer, and notify your embassy. A free first visit from a duty lawyer is available [10].
• A positive blood test can lead to charges, whether or not you knew what you took [9].
• Convicted drug traffickers have received 6 to 17 years and fines of ¥3 to 4 million [9].

Then come the immigration consequences. A drug conviction is a ground for deporting a foreign national, and the Immigration Act refuses landing to anyone convicted of drug offences in Japan or any other country [11]. For more on this, see Japan cannabis penalties for foreigners.

The only reliable plan

• Bring no cannabis, THC vapes, THC edibles or CBN products to, through or out of Japan [1][3][7].
• Check any CBD product against Japan's limits before you pack it, or leave it at home [8].
• Check bags, jackets and gadgets you've used in countries where cannabis is legal.
• Never carry a bag or parcel for someone else.
• Declare honestly and use the red channel if you're unsure about anything [1].

Want the whole picture?

This page covers the airport. The HighAbroad Tokyo Guide covers the trip around it: CBD limits and the pre-check, medicine permits, how detention works step by step, emergency contacts, everyday rules visitors trip over, and the culture around all of it. US$4.99, with every claim numbered and dated.

Stay informed, not detained. Get the full Tokyo guide →

Sources

1. Japan Customs, "Procedures of Passenger Clearance" (declaration, green and red channels, prohibited articles). Accessed 23 Oct 2026. customs.go.jp
2. Japan Customs, Customs Answer FAQ 2001, "Articles prohibited from importation" (Customs Act Arts. 69-11 to 69-20). Accessed 23 Oct 2026. customs.go.jp
3. Japan Customs, "関税法の罰条" (Customs Act penalty provisions: Arts. 109, 109-2, 118; notice disposition), Japanese. Accessed 23 Oct 2026. customs.go.jp
4. Japan Customs, Customs White Paper 2025, Chapter VI (detector dogs, X-ray/CT, trace detectors, e-declaration gates as of Apr 2025), Japanese. Accessed 23 Oct 2026. customs.go.jp
5. Ministry of Finance, "令和7年の全国の税関における関税法違反事件の取締り状況" (2025 drug smuggling enforcement), press release. 17 Feb 2026; accessed 23 Oct 2026. mof.go.jp
6. Tokyo Customs, Narita Airport branch, 2025 enforcement figures (cannabis and THC products), Japanese. 17 Feb 2026; accessed 23 Oct 2026. customs.go.jp
7. Ministry of Health, Labour and Welfare (MHLW), "About the Penalties for Drug Offenses in Japan" (English leaflet). Accessed 23 Oct 2026. mhlw.go.jp
8. Tokyo Customs, "18. CBD関連製品" (CBD-related products: THC limits, proof, abandonment), Japanese. Accessed 23 Oct 2026. customs.go.jp
9. UK FCDO, Japan travel advice: "Safety and security". Accessed 23 Oct 2026. gov.uk
10. UK FCDO, "Information Pack for British Prisoners in Japan: Arrested". July 2025. assets.publishing.service.gov.uk
11. Ministry of Justice, Japanese Law Translation, Immigration Control and Refugee Recognition Act, Arts. 5 and 24 (English translation; may predate the 2024 amendments). Accessed 23 Oct 2026. japaneselawtranslation.go.jp
12. Moji Customs, "Drug detector dogs" Q&A (English). Accessed 23 Oct 2026. customs.go.jp