To correctly obtain the reduction of a pad, and easily check the timing of replacement of the pad by providing the color charge in the thickness direction of a abrasive pad.

Though uniformity of the grinding speed in a wafer surface is stable to a certain degree of the integrated time, uniformity is gradually deteriorated during the use in a long time. A foamed abrasive pad 1 is colored to an upper layer. In an actual use, the abrasive pad 1 is held using the adhesive 2 on a grinding surface plate 3, and the loss of a colored part 1a of the upper layer and appearance of a part 1b are understood from the change in color. That means, when the value of uniformity of the grinding speed in the wafer surface exceeds a certain value, the abrasive pad 1 is provided with the changes in color, etc., and the timing of replacement of the pad can be understood without measuring the change in uniformity.