Disclosed is a cylindrical sliding bearing consisting of an upper and a lower half bearings, which supports a crankshaft of an internal combustion engine. An oil groove is formed circumferentially on an inner surface of at least the upper half bearing. There are provided circumferential grooves formed by boring machining on the overall inner surfaces of the half bearings. Each of the circumferential grooves existing in circumferential both end regions has a larger cross-sectional area than the grooves existing in other regions receiving predominantly operational load when the crankshaft rotates. The upper half bearing is chamfered at a front inner end edge with respect to a rotational direction of the crankshaft supported by the sliding bearing, and the lower half bearing is also chamfered at an inner end edge adjacent to the above front inner end edge, an area of the respective chamfered portion being the same as the 0.15 mm to 0.4 mm length chamfer corner area.