PURPOSE: To conduct the mold release of an expansion molded form automatically without requiring the manual operation of an operator by disposing at least one ejector pin driven by a cylinder to at least one of a top force and a core mold.

CONSTITUTION: A molding die for molding a product such as a seat back cushion has a bottom force 11 and a top force 12 joined with one side section of the bottom force 11 by a hinge, and the top force 12 has a core corresponding section 12b corresponding to a core mold besides an original top force section 12a. In such a molding die, sleeves 13, 16 protruded to the rear sides of the lower end section and upper end section of the core corresponding section 12b are supported slidably by ejector pins 14, 17 at the lower end section and the upper end section in the opened attitude of the top force 12. Each ejector pin 14, 17 is connected to driving cylinders 15, 18 mounted on the top force 12 respectively, and each ejector pin 14, 17 is projected to the molding surface side of the core corresponding section 12b by operating these driving cylinders 15, 18, thus mold-releasing the product.