The weapons were launched from South Pyongan province in an easterly direction over the sea
North Korea fired two short-range projectiles on Thursday, the South's military said, with nuclear talks between Pyongyang and Washington at a deadlock.
The weapons were launched from South Pyongan province in an easterly direction over the sea, Seoul's Joint Chiefs of Staff said in a statement.
They flew 370 kilometres at a maximum altitude of 90 kilometres, they said, adding: "We are maintaining readiness and monitoring in case of additional launches."
It is the latest in a series of launches by the North but the first since October 2, when it fired a sea-launched missile in a provocative move - a submarine-based missile capability would change the military balance.
The North then walked away from working-level nuclear talks with the US in Sweden, saying it was disappointed at the lack of "new and creative" solutions offered by Washington.
Pyongyang is under multiple sets of international sanctions over its nuclear weapon and ballistic missile programmes, which it says it needs to defend against a possible US invasion.
It is demanding the easing of the measures and has repeatedly urged Washington to come forward with a new offer by the end of this year.
The South's National Security Council expressed "strong concern" over Thursday's launch and Japanese Prime Minister Shinzo Abe condemned it, saying it "threatens peace and stability of the country and the region."
The North had carried out more than 20 launches this year, he told reporters: "It is clear that the objective is to improve its missile technologies. It is necessary to further strengthen our security surveillance."
Japan's defence ministry described the weapon as "like a ballistic missile." Pyongyang is banned from ballistic missile launches under UN Security Council resolutions.