A spokesman for the Joint Chiefs of Staff in Seoul said the North had fired what appeared to be two short-range missiles from its western province of Hwanghae into the Sea of Japan off its eastern coast.
"We suspect they were short-range ballistic missiles", the spokesman told AFP.
The latest test came after the North vowed last week to push ahead with further strategic guided-missile tests, defying international calls to curb its weapons programme.
North Korea has conducted a series of missile tests in the past week - seen by some as a display of pique with Chinese President Xi Jinping's two-day state visit to Seoul.