Abstract: A bonded wafer comprising a filmy bond wafer, a base wafer, and an intermediate silicon dioxide layer, wherein the periphery of the bond wafer is etched; this bonded wafer is made by: subjecting the bond wafer to an oxidation treatment to form an oxide film over it; joining the two wafers in a manner such that the oxide film-covered face of the bond wafer is put on the base wafer to thereby sandwich the oxide film between the wafers; heating the combined wafers to thereby create a bonding strength between the two wafers; grinding the exposed face of the bond; etching the periphery of the bond wafer to remove the portion which is not in contact with the base wafer; and polishing the exposed face of the bond wafer until it becomes a thin film.