To obtain a flat surface which has no protrusion on the surface caused by the residual of abrasives by conducting a finish grinding for a circular shaped substrate employing an artificial leather suede pad, while water is being supplied.

In the production of an information record medium substrate, a finish grinding of the substrate is conducted by an artificial leather suede pad, while water is being supplied. Thus, an information record medium substrate, in which no protrusion caused by the residual of abrasives exists on the surface and having a smooth surface (or a smooth surface having reduced number of protrusions), is realized and the amount of floating of a head is reduced. The finish grinding of the substrate is effective not only for the information record medium substrate, to which a low temperature type ion-exchange process is conducted, but also for the information record medium substrate, for which the low temperature type ion-exchange process has not been applied. A suitable PH value of the water used for the finish grinding is 4 to 10. Pure water, ion-exchanged water, and tap water can be used as the water. Buffer solution may be used with the water.