A resin transfer molding (RTM) molding device is designed to mold a fiber-reinforced plastic (FRP) molded body by injecting a resin composition into a mold and by impregnating the molded body therewith. The resin composition is a chain curing polymer (CCP). A CCP accommodating layer is disposed adjacent to an outer side of the molded body. The layer contains the CCP. The layer is provided with a Vf limit value, the value defined by the curing characteristics of the CCP and the characteristics of dissipation of heat from the CCP to the exterior. An element for separating the molded body is disposed between the body and the layer.