The launch, from the eastern area of Wonsan, may have failed, the Japanese agency said. The type of missiles involved was unknown.
Reuters quoted a U.S. Pacific Command spokesman who said the American military had detected “a failed North Korean missile launch attempt”.
The missile “appears to have exploded within seconds of launch,” the spokesman added.
South Korea's defense ministry said it was trying to confirm the report of the missile launches, according to Reuters.
The failed missile launch came days after North Korea tested a powerful new rocket engine, a test hailed by its leader Kim Jong Un as a "new birth" for the nation's rocket industry.
Earlier this month, North Korea fired four ballistic missiles into the sea off Japan's northwest coast.
Wednesday’s reported test came merely hours after a North Korean official made clear his country would continue the "acceleration" of its nuclear and missile programs despite the United States’ threats to impose sanctions on it.