A sliding bearing which comprises a semi-annular first split bearing and a semi-annular second split bearing, which is provided on a cylinder block in a state in which circumferential end surfaces of the first split bearing and circumferential end surfaces of the second split bearing abut against each other, and which supports a journal portion of a crankshaft, wherein the first split bearing and the second split bearing have the same outer diameter; a thickness of the second split bearing at a circumferentially central position is greater than a thickness of the first split bearing at a circumferentially central position; the thickness of the first split bearing is decreased from the circumferentially central position toward the circumferential end surfaces of the first split bearing so that the circumferential end surfaces of the first split bearing have a first thicknesswise dimension; and the thickness of the second split bearing is decreased from the circumferentially central position toward the circumferential end surfaces of the second split bearing so that the circumferential end surfaces of the second split bearing have a second thicknesswise dimension, wherein, in a state in which the sliding bearing is provided on the cylinder block, a point which deviates, from a reference point which is a center of a circle along an outer circumference of the sliding bearing, by a first offset amount toward a circumferentially central position of an inner circumferential surface of the second split bearing is defined as a first center, and a circumferentially extending inner circumferential surface of the first split bearing is an arcuate surface extending along a first reference circle whose center is located at the first center and whose radius is equal to a first reference distance from the first center to a circumferentially central position of the inner circumferential surface of the first split bearing, wherein, in a state in which the sliding bearing is provided on the cylinder block, a point which deviates from the reference point by a second offset amount toward the circumferentially central position of the inner circumferential surface of the first split bearing is defined as a second center, and the circumferentially extending inner circumferential surface of the second split bearing is an arcuate surface extending along a second reference circle whose center is located at the second center and whose radius is equal to a second reference distance from the second center to a circumferentially central position of the inner circumferential surface of the second split bearing, and wherein the first offset amount is rendered smaller than the second offset amount, and the first reference distance is rendered shorter than the second reference distance, whereby the first thicknesswise dimension and the second thicknesswise dimension are rendered equal to each other. the first split bearing and the second split bearing have the same outer diameter; a thickness of the second split bearing at a circumferentially central position is greater than a thickness of the first split bearing at a circumferentially central position; the thickness of the first split bearing is decreased from the circumferentially central position toward the circumferential end surfaces of the first split bearing so that the circumferential end surfaces of the first split bearing have a first thicknesswise dimension; and the thickness of the second split bearing is decreased from the circumferentially central position toward the circumferential end surfaces of the second split bearing so that the circumferential end surfaces of the second split bearing have a second thicknesswise dimension, wherein, in a state in which the sliding bearing is provided on the cylinder block, a point which deviates, from a reference point which is a center of a circle along an outer circumference of the sliding bearing, by a first offset amount toward a circumferentially central position of an inner circumferential surface of the second split bearing is defined as a first center, and a circumferentially extending inner circumferential surface of the first split bearing is an arcuate surface extending along a first reference circle whose center is located at the first center and whose radius is equal to a first reference distance from the first center to a circumferentially central position of the inner circumferential surface of the first split bearing, wherein, in a state in which the sliding bearing is provided on the cylinder block, a point which deviates from the reference point by a second offset amount toward the circumferentially central position of the inner circumferential surface of the first split bearing is defined as a second center, and the circumferentially extending inner circumferential surface of the second split bearing is an arcuate surface extending along a second reference circle whose center is located at the second center and whose radius is equal to a second reference distance from the second center to a circumferentially central position of the inner circumferential surface of the second split bearing, and wherein the first offset amount is rendered smaller than the second offset amount, and the first reference distance is rendered shorter than the second reference distance, whereby the first thicknesswise dimension and the second thicknesswise dimension are rendered equal to each other.