To prevent damage to a boat body and delay of starting of operation even when high waves occur, and easily recover the boat.

In this lifting device a small-sized boat mounted on a mother ship is detachably hung by a cradle 4 which is bent into a substantially J- character form to the outer side of the ship from the view of a bow. The cradle 4 is vertically moved between the mother ship and water level together with the small-sized boat by means of a wire rope operated by a winch on the side of the mother ship. In such a case, a plate spring 26 which can be elastically deformed by self weight of the small-sized boat is briged between the upper and lower ends of the cradle 4. A cushion member 27 is arranged on the plate spring 26 for absorbing shock from the side of the small-sized boat.