A selectively permeable membrane reactor includes a reaction tube including a supply port as an inlet port for a raw material gas and a discharge port as an outlet port for an unseparated gas, and a separation tube inserted into the reaction tube. The separation tube includes a selectively permeable membrane exhibiting selective permeability for a specific component on a surface facing the internal space of the reaction tube, and a process port as an outlet port for a separated gas which has passed through the selectively permeable membrane, and a catalyst for promoting a chemical reaction is provided in the reaction tube excluding the separation tube. A catalyst is carried by a foamed body having porous structure to form a foam-molded product and suppresses physical and chemical deterioration in the selectively permeable membrane and allows a mixed gas produced by a catalytic reaction to be efficiently separated.