PURPOSE: To make the taking-in and out operation of boat easier by a method in which the front side of a housing shed on a wharf is extended to water surface, a boat supporter and a crane with an elevator are provided, and a boat is automatically put in or taken out of left and right-handed multi-layer stage racks.

CONSTITUTION: The first floor of building is formed in a wide space for operation, and its front side is extended to water surface. A mobile crane 10 is set on a rail 13 and racks 2a with a base seat 29 are set on both sides of the rail 13. An elevator 11 for a carrier 20 is also provided to the crane 10, and a fork part 22 consisting of two reciprocal forks is provided to the carrier 20. A boat 4 is supported by the part 22, lifted up from the water surface, washed on the first floor, and transported to a desired place. The part 22 is further advanced to move the boat 4 on the seat 29. Narrow place can thus be utilized effectively and the taking-in and out operation and washing operation of boat can be made easily.