A sliding bearing is constructed by an upper split bearing half and a lower split bearing half. The upper split bearing half has a sliding surface, in which an oil groove which allows a lubricating oil to flow therein is formed over the entire circumferential extent of the sliding surfaced. The oil groove extends through a crush relief to be open to a junction area, and the oil groove has a bottom which is formed so that a portion disposed toward the junction area as considered in the circumferential direction of the crush relief is located closer to the center of the upper split bearing half in comparison to a central portion. An ingress in large quantities of foreign particles within the oil groove onto the sliding surface of the sliding bearing and into a connecting rod bearing after passing through a lubricating oil feed passage is suppressed, and an oil leakage through the crush relief is reduced, allowing a lubricating oil pressure to be secured and augmented.