A Japanese man who was swept 15 kilometres out to sea in the tsunami was plucked to safety yesterday after being spotted clinging to wreckage, officials said.

A Maritime Self-Defence Force destroyer rescued Hiromitsu Shinkawa, 60, after discovering him floating on a piece of roof in waters off Fukushima prefecture two days after the disaster struck.

Rescued ... Hiromitsu Shinkawa was floating on a piece of roof. Credit:AP

The man, from the city of Minamisoma, which was destroyed, was swept out along with his house after the tsunami.

He was conscious and in ''good condition'' after his rescue, ministry officials said, adding that he was taken to hospital by helicopter.