A package manufacturing method capable of easily manufacturing a penetration electrode-attached base board having excellent shape accuracy with a high degree of flatness without forming cracks or the like is provided. The package manufacturing method includes an insertion hole forming step of forming insertion holes in one surface of a base board wafer so as not to penetrate through the base board wafer; a core portion insertion step of inserting conductive core portions made of a metal material into the insertion holes; a welding step of heating the base board wafer to a temperature higher than the softening point of the glass material so as to weld the base board wafer to the core portions while holding the one surface side of the base board wafer with a receiving mold and pressing the other surface of the base board wafer with a flat pressurizing mold; a cooling step of cooling the base board wafer; and a polishing step of polishing both surfaces of the base board wafer.