PURPOSE: To prevent water droplets from developing at core vents, foaming agent from entering the core vents and the core vents from coming off a mold during foam molding and improve the releasing property of a molded part by a structure wherein the core vents, which are made of resin and, in addition, the cross-sectional shape of pipes passing with pyrogenetic vapor and the air of each of which is made circular, and further the outer periphery of each of which has a shape to be obtained by knurling.

CONSTITUTION: A foam molded part 2 is molded by expanding and foaming the foaming agent poured in a mold with pyrogenetic vapor past through core vents 1, each of which has 42 holes with 0.4mm in diameter and 10mm in depth and is made of polyphenylene sulfide (PPS) resin. When the mold is open, the air is flowed through the core vents 1 so as to release the foam molded part 2 from the mold under air pressure. Because PPS resin core vents are employed, the core vents can be set in the mold noiselessly and the coming-off of the core vents is prevented from occurring. In addition, no water droplet develops in the core vent. Further, the molded part is surely released from the mold.