To provide a stacking device having a simple configuration necessitating no positioning means and position sensor and capable of easily coping with various kinds of articles.

A resin box 4 is supported on a support means 7 moved by an arm part 6 of a robot 2, the resin box is loaded on a resin box loaded on a carrier 5, and the support means lowers by a predetermined amount to release support of the resin box. The arm part rotates and moves the support means in the horizontal direction to move the resin box positioned at an upper step in the horizontal direction relative to the lower resin box by the support means. The upper step resin box 4A moves for the lower step resin box 4B so that a projecting part 4d of the upper step resin box is fitted into an opening part 4c of the lower step resin box, and the upper step resin box drops due to its self-weight to stack upper and lower resin boxes normally.