Occupant discriminating method for vehicular seat

A flat spring (15) of a vehicular seat (10) is elastically supported by means of supporting springs (23a to 23f) that extend in accordance with the load of an occupant. The seat (10) has displacement sensors (16a to 16d), first-stage determination step (ST100), second-stage determination step (ST200), and third-stage determination step (ST300). The displacement sensors output electrical signals corresponding to the respective elongations of the springs (23a, 23c, 23d, 23f). The first-stage determination step determines the occupant in the seat (10) in accordance with voltage values delivered from the displacement sensors. The second-stage determination step determines whether or not the result of determination by the first-stage determination step is maintained for a given period of time. The third-stage determination step compares the result of determination by the second-stage determination step with the preceding result of determination and specifies the occupant in accordance with the result of the comparison.