A molding device for manufacturing a molded product having an inner space bent in a circular arc shape includes: a set of molds joinable to and separable from each other, the set of molds being capable of forming a cavity having a shape corresponding to an outer shape of the molded product in a joined state at the time of molding; a core having an outer shape corresponding to an inner shape of the molded product for use in a state where the core is arranged in the inside of the cavity formed by the set of molds at the time of molding; and an ejector plate having a core through hole through which the core passes for ejecting the molded product formed around the core along the circular arc shape in a separated state where the set of molds is separated from each other.