An object is to provide a device and method for manufacturing a fiber-reinforced plastic molded article, whereby two members can be accurately positioned with respect to each other upon integral molding of the members via a VaRTM method. A device for manufacturing a fiber-reinforced plastic molded article includes a skin mold in which a skin, which is a cured fiber-reinforced composite member, is mounted; a stringer mold that is configured to accommodate a stringer, which is a fabric to be joined to the skin; and a folded plate that is configured to accommodate the stringer mold and includes a positioning portion for positioning with respect to a positioning portion provided on the skin.