PURPOSE: To simplify constitution of a whole unit without casting the necessity for using a hydraulic cylinder, wires, etc., by mounting a seabottom working machine and its connection pipes or the like to a mounting bed on a ship body through a supporting device consisting of a gear lift device and engaging device.

CONSTITUTION: As the device suspensively supporting, for instance, a large gathering machine 11 of a mining ship gathering an oceanic mineral of manganese mass or the like distributed to the deep seabottom and a gathering pipe 13 and its accessory connected to this machine 11, a lift suspension supporting device 15 comprising a rack 21 and engaged pinion gear 9 is arranged to a mounting bed 7 on a ship body 1. A stopper device is provided to the device 15 together with a lift device by the rack 21 and the pinion 9, and lift action and stop action are repeated in a measuring state to perform lift work of the machine 11 and the pipe 13. As compared with a conventional device of hydraulic wire driven type, constitution of a whole unit can be simplified.