PURPOSE: To be able to mold with excellent mold releasability without using a mold release agent by disposing a resin sheet having mold releasability previously formed in a mold surface shape on a least one mold surface of split molds.

CONSTITUTION: A predetermined quantity of a foamed resin is injected from an injection port in a cavity space formed between a resin sheet 10 for an upper mold and a resin sheet 20 for a lower mold after the upper mold 1 and the lower mold 2 are closed, and foam-molded. Since the formed molding has mold releasability at the sheet 10 for the upper mold and the sheet 20 for the lower mold, it is easily released, and the sheet 10 for the upper mold and the sheet 20 for the lower mold are again used for molding. Accordingly, since the molding can be conducted almost without using the agent, various malfunction due to the agent is avoided.