A passenger protection apparatus comprises an airbag having a concaved receiving portion at its specified position which corresponds to a face of a small-sized passenger seated in a passenger's seat when the airbag inflates in a vehicle collision, an inflator supplying gas to the airbag in a collision of a vehicle to inflate the airbag before the passenger's seat, a position sensor detecting a longitudinal sitting position of the passenger seated in the passenger's seat, and a seatbelt device, an airbag unit for pop-up seat, and a knee airbag unit which adjust a restraint position of the passenger in accordance with the longitudinal sitting position of the passenger so that the face f the small-sized passenger is received at said receiving portion of the airbag in the vehicle collision.