The one-ton wooden boat was found Monday about 50 kilometers (30 miles) northeast of Ulleung Island off the east coast, an official of South Korea 's spy agency said.
The boat had been drifting for 27 days after its engine broke down, the official said on condition of anonymity, because he was not authorized to speak to media.
"We plan to handle this case by respecting the intention" of the North Koreans, the official said, adding intelligence officials were trying to confirm whether they wanted to be returned home.
Some North Koreans have defected by sea to South Korea , but Seoul regularly repatriates North Korean crews when they express their desire to return home.
The two rival Koreas remain technically at war since the 1950-53 Korean War ended in a cease-fire that has never been replaced by a peace treaty.