An air conditioner for a vehicle which can reduce ventilation resistance and secure a sufficient cross-sectional area of an air outlet to prevent deterioration in air volume. The air conditioner includes: an air-conditioning case having an air passageway formed therein and a plurality of air outlets formed at an exit thereof, and at least one heat exchanger disposed in the air passageway of the air-conditioning case to exchange heat with air passing through the air passageway, wherein the air outlet includes a center vent for discharging air-conditioned wind toward the center of a vehicle width and a side vent for discharging the air-conditioned wind toward the side of the vehicle width, and one between the center vent and the side vent is arranged in an upper side of the air-conditioning case, and the other is arranged in one side of the air-conditioning case in a back-and-forth direction of the vehicle.