To provide a compact and inexpensive side shifting device improved in working efficiency thereof over the whole, and to provide a palletizing transportation system using the same, and to provide a palletizing method.

This side shifting device 1 tightly aligns a plurality of works, which are placed on a pallet 2 with an interval by a palletizing robot 103, on the pallet 2 by moving side shifting bodies 3 and 4 having aligning surfaces 3a and 4a in the horizontal direction so as to push the aligning surfaces 3a and 4a to the works. The side shifting bodies 3 and 4 are arranged in pair so that respective aligning surfaces 3a and 4a face the crossing direction. A horizontal driving mechanism is provided to move one shifting body 3 in a direction of the aligning surface 3a thereof, and to move the other shifting body 4 in a direction of the aligning surface 4a thereof.