A production apparatus includes the following stations juxtaposed in the following sequence: a parison forming station for forming a parison; a built-in part attachment station where opposite sides of a center die provided with a built-in part are held between a pair of molding dies to locate the center die in the molding dies with the parison between the center die and the molding dies, and the built-in part being attached to the parison transferred to the molding dies; a molding station where the molding dies are closed to mold the hollow molded product; and a conveyance station for taking the hollow molded product out of the molding dies and conveying the hollow molded product. The center die is fixed at the built-in part attachment station, and the molding dies are configured to be movable back and forth between the built-in part attachment station and the molding station.