An occupant protection apparatus includes an airbag provided at a seat portion of a vehicle seat. The airbag is inflatable in such manner as to push up at least a part of a cushion body of the seat portion. At the time of collision of the vehicle, an ECU permits inflation of the airbag if a sensor senses that an occupant is seated on the seat, and inhibits inflation of the airbag if the sensor senses that no occupant is seated on the seat. Therefore, when no occupant is seated on the seat, inflation of the airbag is inhibited at a vehicle collision.