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