An air conditioner allowing a blade driving device to rotate the blade in the up-and-down direction around the respective rotation axis via the two rotation axis, thereby the blade driving device effectively guides the discharged air in the vertical direction. Further, the blade driving device may efficiently rotate the blades by including one or two driving motors for rotating the blades, minimizing the volume of the blade driving device, thereby the blade driving device reduce the size of the air conditioner or efficiently reducing the internal space of the air conditioner.