PURPOSE: To attain boarding aboard and leaving from a ship without generating large rolling in a ship body.

CONSTITUTION: A cockpit 2 is formed in the central part of a ship body 1, and in a front side of this cockpit, the first passage means 3, where a later 9 for on-off getting a ship to the cockpit 2 is extendably/storably mounted, is formed in a ship body width directional central part. Further in a constitution, an operator's seat 4 is formed in the rear side of the cockpit 2, the second passage means 5 for operator on-off getting the ship is formed in a rearward side of the operator's seat, a propeller is arranged in a lower side of the operator's seat 4, and the ladder 9 can be switched from a grounded condition to a storage condition onto a deck so that the other end part of the ladder 9 is grounded in a condition that its one end part is held by a bow part.