PURPOSE: To reduce height and improve starting force in a bottom floor type lifting device by connecting the lower end of an operating rod rotatably to the lower end part of a cylinder device, and interlocking the upper end of the operating rod with the connecting pin of an inner and an outer arms through a cam member so as to open the inner and outer arms by the elongation of a cylinder.

CONSTITUTION: When a hydraulic cylinder 17 is elongated at the time of a lifting device being in a lowered position, a roller 33 moves in the direction of an arrow mark M1 along a rail member 34. An operative connecting plate 31, an operating rod 41 and rollers 43, 44 thereby move also in the direction M1. The rollers 43, 44 push cam members 51, 52 and open while rolling on cam faces 51a, 52a so as to rotate an outer arm 11 and an inner arm 12 around a shaft pin 13 to open the arms 11, 12. When the roller 33 stops coming in contact with a stopper member 35, a table 14 is pushed up by a piston rod 17, and the inner and outer arms 11, 12 are further opened to lift the table 14 up to the lifting limit.