PURPOSE: To improve the weight balance of a lifter which has a pantograph mechanism between a fixed base board and a elevating board, and to lower the lowest position of an elevating plate.

CONSTITUTION: Rotary nuts 22 and 23 screwed with a pair of screw shafts 19 and 20 which are connected to wedge rollers rolling-contacted to the opposite surface of links 4 and 5 at the free end side of a crossing link are housed together with a reduction gear train in a gear case 21 provided integrally with the shaft 6 of the crossing link, and a driving motor 31 is connected to the rear surface side of the gear case 21.