An occupant detecting apparatus includes a detecting portion detecting whether an occupant is seated on a seat, and a judging portion judging whether the occupant occupies the seat on the basis of information detected by the detecting portion. The judging portion judges that the seat is unoccupied by the occupant when a state where a detection that the occupant is not seated on the seat by the detecting portion continues for a judgment time after the detecting portion detects that the seat is occupied by the occupant.