To provide a semiconductor wafer having dot marks produced by irradiating laser beam capable of selecting a marking region capable of reading and writing marks in a state in which the marks hardly vanish and the semiconductor wafer is contained in a wafer cassette, inscribing information of an identification number or electric properties in the region and grasping past history by a unit of the wafer in processing steps or semiconductor fabrication steps thereafter, a very small dot mark is formed by irradiating laser having a diameter of 1 through 13 &mgr;m on an inner wall face of a notch (1) formed on an outer peripheral face of a semiconductor wafer (W), particularly on an inclined face of its peripheral edge.