To elevate a large hull by low cost facilities, to save a crew for elevation of the hull and to facilitate boarding and unboarding of passengers.

This device is furnished with a travelling base 2 arranged free to elevate along a slope S between the land and the sea, a carriage placing base 9 fixed on the travelling base in a horizontal state and a hull control facility 12 provided on the side of the carriage placing base. Thereby, the hull control facility 12 is furnished with a plural number of vertical supports 15, 20 erected in parallel in two rows against the carriage placing base 9 and a platform 21 fixed between these parallel and vertical supports.