A car air-conditioning duct guides air to a suction side of an air conditioner mounted on a car or guides the air flowing from a blow-off side of the air conditioner. The car air-conditioning duct includes a duct wall having a tubular shape and forming a duct outer surface and a duct inner surface. The duct wall is made of a composite foamed resin material containing polystyrene resin and polyolefin resin.