To provide an air conditioner having a drainage pump which is constituted to reduce its drive noise and to prevent the reverse flow of pumped water.

This air conditioner has the drainage pump provided with a pump case 20 having a suction opening which is dipped in a condensate in its bottom face and a discharge port in its side face, an impeller 43 which is rotatably provided in the case 20, and a motor which drives the impeller 43. The drainage pump is also provided with a noise insulating member 50 which wraps the external surface of the case 20 so as to intercept the drive noise of the pump, and is further extended downward from the lower end of the suction opening and a check valve 60 which is installed to the discharge port to prevent the reverse flow of a discharged condensate.