A hydro dynamic bearing device comprising an upper half of a main bearing and a lower half of the main bearing, wherein the upper half of the main bearing is lined with a low-strength metal such as a Babbitt metal, wherein a circumferential groove is formed in the lower half of the main bearing, and wherein the low-strength metal of the upper half of the main bearing, which is formed at a region opposed to a downstream side of the circumferential groove formed in the lower half of the main bearing, is partially removed to cause a high-strength bearing base metal to be partially exposed.