To make a substantial reduction of physical burden of a worker during a cargo loading or a cargo unloading and further to cause this operation to be attained simply and easily.

This working lifter device 13 is comprised of a supporting column 14 arranged at a rear surface 4 of a tank 2 of a tank rolley 1 and installed in a vertical orientation at the rear surface 4 of the tank 2; a main body 15 of the device liftable between one location near the ground surface A and the other location near the upper surface 3 of the tank 2 while being held and guided by the supporting column 4 and having a footing 20; pulleys 16 arranged near an upper part and a lower part of the rear surface 4 of the tank 2, respectively; an endless belt 24 applied between the upper and lower pulleys 16 and connected to the main body 15 of the device; a motor 18 connected to the pulleys 16 and for running the belt in normal or reverse direction; and a switch 19 arranged at the main body 15 of the device so as to control the operation of the motor 18.