The invention provides a bearing device, including a crankshaft, a pair of half bearings each having crush reliefs adjacent to both circumferential ends thereof, a bearing housing having a retaining hole, and one half thrust bearing arranged adjacent to the retaining hole. Each half thrust bearing is configured at least by a bearing alloy layer and a resin slide layer which constitutes a slide surface receiving an axial force of the crankshaft, and thrust reliefs adjacent to both circumferential end portions of the sliding surface so that its wall thickness is made thinner toward the circumferential end surface. A thrust relief length at an inner end portion of the thrust relief positioned on a rear side in the crankshaft rotational direction is formed to be larger than a thrust relief length at an inner end portion of the thrust relief positioned on a front side.