To provide a work loading method of an automatic palletizer with which installation area of a plurality of robots is small, any interference between the robots is eliminated, and a short cycle time is realized.

A work (W) is positioned at every other press shot 1 by two centering devices (3a and 3b) on the upstream and downstream sides in the carrying direction, and one set of the two robots (4a and 4d) and (4b and 4c) diagonally positioned out of the four robots with two robots each facing each other on the right and left sides of the carrying direction across the two centering devices hold the work (W) on the centering device alternately one time at every time when the work (W) is positioned by the two centering devices (3a and 3b), and load the work on a pallet (6). The loading position is controlled based on the number of the works already loaded on the pallet before the works are loaded, and the number of the already loaded works.