Disclosed are provided an air conditioner having a door that can be smoothly moved by a friction member. The air conditioner includes a main body configured to form an outer appearance, an outlet provided in a lower portion of the main body, and configured to discharge air, a door disposed in a front portion of the main body, and configured to open or close the outlet, a driving device including a pinion configured to be rotatable, and a rack interlocked with the pinion and configured to be movable together with the door; and a friction member configured to press the rack when the rack moves so as to maintain a predetermined spacing between the rack and the pinion. The rack and the door can slide smoothly along a curved path through the friction member by a force of the motor.