An air conditioner includes a housing including an inlet and an outlet, and a blade rotatably provided to open and close the outlet. A blade drive device is connected to one end of the blade in a longitudinal direction of the blade to rotate the blade. A blade support unit is configured to rotatably support the other end of the blade in the longitudinal direction of the blade. The blade support unit includes a coil spring configured to apply torque to the blade and a blade holder is coupled to the other end of the blade. A first coupler is coupled to the coil spring, and is configured to penetrate the coil of the coil spring. A case is configured to accommodate the first coupler of the blade holder and is mounted to the housing. The air conditioner is capable of reducing deformation and noise in a blade.