To provide a multistage stacking method of an apparatus with a moving caster, and an interposing seat tool for easily stage-stacking a large number of products without requiring troublesome wooden frame packing, and without using a special carriage.

This apparatus 1 with a plurality of moving casters is formed by attaching a suspender 3 to an upper surface by arranging the plurality of moving casters 2 on a bottom surface, and stacks the plurality of moving casters in a multistage shape in a mode of fitting the suspender 3 of the downwardly positioned apparatus 1 in a recessed part 6 in an under surface of the seat tool 4, and fitting the casters 2 of the upwardly positioned apparatus 1 in a recessed part 5 in an upper surface of the seat tool 4 by interposing the seat tool 4 for arranging the moving caster fitting recessed part 5 on the upper surface, and arranging the suspender fitting recessed part 6 on the under surface.