SEAT DEVICE

A seat device 5 according to the present invention includes a cushion pad 60, a support member 70 for supporting the cushion pad 60, a pressure sensitive switch SW disposed with a spacing from the under face of the cushion pad, and a pressing member 90 disposed below the cushion pad 60 and deformed by a pressure applied from the under face of the cushion pad to press the pressure sensitive switch SW. The deformed amount of the pressing member 90 per unit displacement amount in which the under face of the cushion pad is displaced downwardly is greater in a second stage after the pressure sensitive switch SW is turned on than in a first stage before the pressure sensitive switch SW is turned on.