There is provided a method for processing a semiconductor wafer subjected to a chamfering process, a lapping process, an etching process, and a mirror-polishing process, wherein acid etching is performed after alkaline etching as the etching process, and the acid etching is performed with an acid etchant composed of hydrofluoric acid, nitric acid, phosphoric acid, and water, a method for processing a semiconductor wafer subjected to a chamfering process, a surface grinding process, an etching process, and a mirror-polishing process, wherein the etching process is performed as described above, and a method for processing a semiconductor wafer subjected to a flattening process, an etching process, and a mirror-polishing process, wherein the etching process is performed as described above, a back surface polishing process is performed after the acid etching as the mirror-polishing process, and then a front surface polishing process is performed. According to this, there can be provided a method for processing a semiconductor wafer to have good flatness, good surface roughness, and good condition on a back surface thereof.