Japanese crypto exchange Bitbank told users on June 15 that it will suspend accounts tied to deposits or withdrawals involving Polymarket and other prediction market platforms, warning that using such services from inside Japan for profit may amount to illegal gambling. The notice marks one of the clearest moves yet by a licensed Japanese exchange to police the flow of funds between domestic crypto accounts and offshore prediction markets. Bitbank framed the step as part of its duty to follow applicable Japanese law and keep its trading environment safe, and it placed Polymarket at the top of the services it now treats as a compliance risk.
Bitbank Ties Transfers to Gambling Risk
Bitbank described prediction market services as platforms that let users wager crypto on future outcomes such as elections and sports results. The exchange named Polymarket directly and grouped it with other services that carry betting characteristics. Many of these platforms run from outside Japan, the exchange said, but accessing them from within the country to pursue financial gain may fall under gambling activity prohibited under Japanese law.
Bitbank said it may suspend any account where it confirms deposits or withdrawals connected to a prediction market service, or to a service it suspects is linked to one. Polymarket’s own developer documentation supports the jurisdictional picture, listing Japan as a frontend-restricted market where the platform blocks domestic users at its website while leaving its API open.
Suspensions Cut Off Full Account Access
A suspended account loses every core function, Bitbank said. Users can no longer log in, move crypto in or out, withdraw Japanese yen, or buy and sell crypto. The exchange said it will accept no liability for losses caused by a suspension. Customers who believe an account was frozen in error can contact Bitbank through its inquiry form to have the case reviewed. Bitbank closed the notice by urging users to take care with external services so they do not unknowingly become involved in criminal activity.
The warning lands as regulatory pressure on Polymarket builds across several jurisdictions. Ukraine moved to block domestic access to Polymarket on January 12, 2026, after its regulator classified the platform as unlicensed gambling and added the domain to a national registry of prohibited sites. Polymarket has also tightened its terms of service and market integrity rules to curb insider trading and manipulation, as legal scrutiny mounts in the United States. Polymarket has separately signaled longer-term ambitions in Japan, appointing a local representative and preparing to lobby for approval to operate prediction markets in the country by 2030.
