a method of molding a plastic resin having for its object to enable the filling or spreading speed of a molten resin in a mold to be controlled in compliance with the shape of an article to be molded by changing the opening and closing speed of the mold or the injecting speed of the molten resin in an injection unit in compliance with the amount of the molten resin charged into the mold or the amount of the molten resin injected by the injection unit so that a stable molded article can be produced in a short time even in case the shape of a product to be molded is changed , and an injection - compression molding machine constructed to achieve the molding method . this injection - compression molding machine has a compression unit for clamping the mold , an injection unit for injecting the molten resin into the mold , a detector for detecting the stroke of the compression unit , a detector for detecting the opening and closing speed of the mold , input component for setting inputs of the stroke of the compression unit , the opening and closing speed of the mold , and the injecting speed , respectively , a controller including an interface , a compression unit driving component , and an injection unit driving component .