The reported test follows an attempted launch last month that South Korea said failed in its initial flight stage.
North Korea, believed to be developing nuclear weapons, is banned by the UN from any use of ballistic missiles.
The latest launch comes after Pyongyang threatened retaliation for joint US-South Korea military exercises that it sees as a rehearsal for invasion.
Last month, the US and South Korea also agreed to deploy a missile defence system to counter threats from the North.
In January, North Korea conducted its fourth nuclear test, claiming it to be its first using a hydrogen bomb.
Shortly after that Pyongyang launched a satellite, widely seen as a test of long-range missile technology.