To carry out efficiently and safely the foam molding for a body with composite members on both faces.

The cavity sides of two pairs of molds A and B are movable in the X axial direction, and the core sides are movable in the X and Y axial directions. Two pairs of molds can be opened and closed alternately. (A) Molds on both sides are respectively moved in the X axial direction, and a cavity 1a and a core 2a of one mold A are faced each other, while a cavity 1b and a core 2b of a remaining mold B are moved to the position where both are not faced each other (member setting position), (B) the mold A is closed, (C) a forming material is injected into the closed mold A, (D) the mounting work for a composite member is carried out in the mold B, and (E) after the completion of the foam molding operation and also the completion of the composite member mounting work in the mold B, the mold A is opened and a molded product is released. The operations of (A) through (E) are repeated alternately in the two pairs of molds A and B.