The present invention is a method for processing a semiconductor wafer having a front surface, a back surface, and a chamfered portion composed of a chamfered surface on the front surface side, a chamfered surface on the back surface side, and an end face at a peripheral end, including: mirror-polishing of each portion of the chamfered surface on the front surface side, the chamfered surface on the back surface side, the end face, and an outermost peripheral portion on the front surface or the back surface adjacent to the chamfered surface; wherein the mirror-polishing of the end face and the mirror-polishing of the outermost peripheral portion on the front surface or the back surface are performed in one step, after a step of mirror-polishing the chamfered surface on the front surface side and a step of mirror-polishing the chamfered surface on the back surface side, and a roll-off amount of the outermost peripheral portion on the front surface or the back surface is adjusted by the one step-performed mirror-polishing of the end face and the outermost peripheral portion. This provides a method for processing a semiconductor wafer which can form a desired sag shape at the outermost peripheral portion with high accuracy without deforming the shape of the internal side from the outermost peripheral portion of the semiconductor wafer, and can process a semiconductor wafer not to have a sharp edge shape after the processing.