PURPOSE: To efficiently operate a trolley on a hammer head crane in minimum descending time by combining the hammer head crane with a transfer device arranged with a roller conveyor in the lower part and a lift in the upper part.

CONSTITUTION: A hoist 24 of a hammer head crane 21 takes up a single container 25 from a container layer 25 on a ship, a cargo loader-lift 33 or 35 of a transfer device 32 moves to the uppermost position, and a trolley 23 moves the container 25 above a tower 31 to unload a cargo on roller stands 70, 72 of the lifts 33, 35 so as to be transferred through roller conveyors 37, 39. When the container 25 is mounted on a ship 27, operation is performed in an inverse procedure. Thus, a trolley is efficiently operated on the hammer head crane in minimum descending time, and a vertical moving distance of the hoist can also be most shortened to efficiently perform cargo handling work of the container.