An air conditioner includes a housing including a front panel provided with at least one opening, and a rear lower panel disposed at a rear side of the front panel, at least one discharge outlet exposed to a front of the front panel through the opening, at least one suction inlet formed in the housing, at least one heat exchanger to exchange heat with external air through the suction inlet, at least mixed-flow fan rotatably disposed between the heat exchanger and the discharge outlet to suction the air having exchanged heat with the heat exchanger and discharge the air through the discharge outlet, and a drain panel disposed at a lower portion of the heat exchanger to collect condensate produced during heat exchange, and integrated with the rear panel through injection molding.