A bonded silicon wafer is produced by a method comprising a step of implanting oxygen ions from one surface of a silicon wafer for active layer to form an oxygen ion implanted layer, a step of bonding the one surface of the silicon wafer for active layer to one surface of a silicon wafer for support layer and then conducting a heat treatment for strengthening the bonding to form a silicon wafer composite, a step of polishing a silicon portion at a side of the silicon wafer for active layer in the silicon wafer composite on a rotating platen having a polishing means and stopping the polishing at a time of detecting change of physical properties on the rotating platen resulting from the exposure of at least a part of the oxygen ion implanted layer and a step of removing the oxygen ion implanted layer.