Abstract: The present invention relates to an air conditioner for a vehicle, which can send air-conditioned air toward a rear seat of the vehicle in order to perform air-conditioning of a front seat of the vehicle and air-conditioning of a rear seat. The air conditioner includes an air passageway formed in an air-conditioning case, wherein the air passageway includes: a rear seat cold air passageway which is a passageway that the air passed through the heat exchanger for cooling bypasses the heat exchanger for heating and flows toward a rear seat of the vehicle; and a warm air passageway which is a passageway that the air passed through the heat exchanger for cooling passes through the heat exchanger for heating and flows toward a front seat or the rear seat of the vehicle.