In supplying a predetermined amount of a molten resin D between an upper mold 10 and a lower mold 20 for compression molding, after the upper mold 10 is moved downward for a predetermined stroke length so that it approaches the lower mold 20 in which the molten resin D has been supplied, a compression load is applied while moving the lower mold 20 upward and supporting the upper mold 10 such that clamping is conducted against the compression load which has been applied to the lower mold 20. As a result, when molding a molded article in a predetermined shape by compression molding, if molds are allowed to open with a sufficient stroke length for taking a molded article out, prolongation of molding cycle can be effectively prevented, whereby a molded product in a predetermined shape can be mass-produced.