North Korea fired what appeared to be a ballistic missile on Thursday (local time), the Japanese government said, according to the Reuters news agency.
The projectile has already fallen into the sea, said the Japanese coast guard.
South Korea’s Yonhap news agency also reported that North Korea had fired a ballistic missile off its east coast, citing South Korea's military.
The North Korean missile appears to have landed outside Japan's exclusive economic zone, Japanese public broadcaster NHK reported.
The launch comes just two days after Japan said that North Korea has informed it of a plan to launch a satellite by June 3.
North Korea launched a satellite on May 31 of last year that ended up plunging into the sea. The North said the botched satellite launch had been the "gravest failure" and announced it will be preparing for another launch in the near future.
In November, North Korea sent its first military reconnaissance satellite into orbit as part of its efforts to build a space-based surveillance network to deal with what it calls US-led military threats.
North Korea, which has tested dozens of missiles in the last year including its first intercontinental ballistic missiles since 2017, has recently upped the rhetoric.
In January, the country launched a hypersonic missile. In response, South Korea, the United States and Japan carried out joint naval drills in waters off southern Jeju Island.
North Korea then announced it had tested an "underwater nuclear weapon system" in response to the joint naval exercises.
Last month, North Korea successfully test-fired a new mid- to long-range solid-fuel hypersonic missile.