Abstract: A mold assembly for producing a molded object from resin. The assembly includes a cavity configured to be filled with resin to form at least one surface of the molded object into a predetermined shape with at least one transfer surface of the cavity. A molding insertion member is arranged to form another surface of the molded object, and a holding insertion piece is configured to hold the molding insertion member. The holding insertion piece includes a communication path that places a surface of the molding insertion member at a side opposite to the cavity in fluid communication with the exterior of the mold assembly and guides air from the exterior of the mold assembly toward the surface of the molding insertion member.