An air conditioner of present invention comprises a housing having an outer panel forming the exterior and an opening formed on the outer panel, a heat exchanger configured to exchange heat with air flowing into the housing, and a door unit configured to open or close the opening by moving forward or backward from the opening through which the heat exchanged air is discharged. Wherein the door unit comprises a door blade configured to open or close the opening, a door operating part configured to move the door blade forward or backward, and a controller configured to control the air discharged from the opening to be moved forward from the opening in a straight line or to be discharged radially from the opening by controlling a distance between the door blade and the opening.