To provide an ashtray mounting device capable of reversing an ashtray not to obstruct a game during disuse.

When the ashtray 41 is not used, the ashtray 41 in the usable state is rotated almost by 180° around both projections 451 as shown by an arrow mark in the figure and then moved backward. Both projections 451 thereby slide respectively on linear parts 453a of both guide grooves 453 and are fittingly inserted in bent parts 453b before long. The ashtray 41 is then moved down, and the upper face of the ashtray 41 in the reversed state abuts on a pedestal 47 to put the ashtray 41 in a state of being enclosed in a holder 43. In this state, a screw is screwed into a screw hole to lock the ashtray 41 out of rotation.