To provide a method of automatically stacking various commodities being conveyed in three stages.

The automatic commodity stacking device comprises a roller conveyor to which one-stage commodities being carried in proper lines are supplied and which has small diameter portions formed corresponding to the proper lines of the commodities. One-stage commodities supplied onto the roller conveyor are detected and the commodities are sucked by a suction disc, moved two or more stages up and supported. One-stage commodities supplied onto the roller conveyor are detected, forks are moved into the small diameter portions of the roller conveyor and moved one or more stage up, and the commodities are supported on the forks. Then, one-stage commodities supplied onto the roller conveyor are detected and the commodities are stacked with the move-down and move-back of the forks as well as the move-down and release of the suction disc.