The present invention provides a sliding bearing which is inexpensive, has a simple construction, and is capable of keeping a frictional torque low. A sliding bearing (1) supports a heat roller such as a fixing roller, a pressure roller, and the like of an image-forming apparatus is constructed of an outer ring (3) and an inner ring (2). The outer ring (3) is made of synthetic resin and the inner ring (2) is made of a sintered metal, or the outer ring (3) is made of a sintered metal and the inner ring is made of synthetic resin. The outer circumferential surface of the inner ring (2) is formed as a convexly curved surface, and the inner circumferential surface of the outer ring (3) is formed as a concavely curved surface corresponding to the convexly curved surface. The outer ring (3) is composed of two radially halved parts. The inner ring (2) is fitted on the outer ring (3) by sandwiching the inner ring (2) between the radially halved parts of the outer ring (3) in such a way that the inner circumferential surface of the outer ring (3) and the outer circumferential surface of the inner ring (2) slide relative to each other.