"South Korea and the United States are aware of the North Korean missile launch," said a spokesman for Seoul's defence ministry, adding they "suspect it was a failure".
The ministry did not identify the type of missile used in the test.
A US Pacific Command spokesman also confirmed that US military had detected "a failed North Korean missile launch attempt" in the vicinity of Kalma, North Korea.
Japanese Kyodo news service, citing an unidentified government source, said the North might have launched several missiles Wednesday morning.
The missiles were possibly launched from North Korea's east, Kyodo's source said, adding that there was information that the launches were a failure.
Nuclear-armed North Korea launched four ballistic missiles earlier this month, with three landing provocatively close to America's ally Japan.
However Japan's chief government spokesman Yoshihide Suga said the government had not yet confirmed North Korea launched any missiles.
"We haven't confirmed any missiles flying towards Japan so we don't think that an incident which is a threat to our national security has arisen," he said.
Suga said the nation is always gathering and analyzing information on the country, and declined to make comments on further details.
The launches come as Seoul and Washington hold large-scale annual joint military exercises that always infuriate Pyongyang, which sees them as a rehearsal for invasion.
Earlier this month, North Korea fired four ballistic missiles into the sea off Japan's northwest coast, angering South Korea and Japan.
