The present invention provides a method of manufacturing a bonded wafer. The method includes forming an oxygen ion implantation layer in an active layer wafer having a substrate resistivity of 1 to 100 mΩcm by implanting oxygen ions in the active layer wafer, bonding a base wafer and the active layer wafer directly or through an insulating layer to form a bonded wafer, heat treating the bonded wafer to strengthen the bond and convert the oxygen ion implantation layer into a stop layer, grinding, polishing, and/or etching, from the active layer wafer surface side, the bonded wafer in which the bond has been strengthened to expose the stop layer on a surface of the bonded wafer, removing the stop layer, and subjecting the bonded wafer from which the stop layer has been removed to a heat treatment under a reducing atmosphere to diffuse an electrically conductive component comprised in the active layer wafer.