PURPOSE: To reduce manufacturing man-hours and cost by a method wherein sure seal between a sealing member and a discharging member is permitted without applying cutting and grinding works while the generation of condensate can be prevented without bonding any insulating material.

CONSTITUTION: A sealing member 14 is mounted to a discharging unit 12, to which a drain hose is not connected, between cylindrical discharging units formed projectingly on holes below both left and right ends of a drain pan main body 10. The sealing member 14 is constituted of a main body 15, inserted into the deep section of the inside of the discharging unit 12B, a seal lip 16 around the outer periphery of tip end substantially and a coating unit 17. PL is not existing on the internal peripheral surface of the discharging unit l2B whereby the seal lip 16 is abutted against the smooth internal surface of the unit 12B by elastic deformation and seal property will never be impaired. Reserved water is sealed by a seal lip 16 whereby the water will never reach the tip end of the inside of the water discharging section 12B while a temperature difference will never be generated substantially between the inside and outside of the discharging unit 12B.