PURPOSE: To provide a wafer having a good roughness of a grinding surface by a method wherein grinding pressure acting at grinding is specified.

CONSTITUTION: For a wafer 2 held by a rotating plate 1, an abrasive 6 is dropped via a nozzle 5 on a grinding cloth 4 adhering onto a grinding base 3 moving relative to each other, while mirror-grinding a surface of the wafer 2. In this embodiment, grinding pressure acting at grinding is set to be 130 to 200gf/cm2. Thus it is possible to obtain a good roughness of a ground surface for a short time and to suppress a remaining stress given to the surface to be ground within an unquestionable range in manufacturing a semiconductor device, therefore it is possible to provide a mirror wafer of high quality with a high efficiency.