A thermally sensitive recording medium has at least one layer on a substrate which is a thermally sensitive recording layer that contains a colorless or pale colored electron-donating leuco dye and an electron-accepting color-developing agent. At least one layer on the substrate contains a hydrated silicic acid compound which is treated by wet grinding treatment in a deposition process of the hydrated silicic acid compound. A thermally sensitive recording medium of high brightness, which is superior in color-developing sensitivity and coating layer strength and, further, has excellent head abrasion resistance, less debris adhering and sticking resistance is obtained.