A plain bearing comprising a housing and two plain bearing halves forming a cylindrical shape in combination and fixed in the housing. Each of the plain bearing halves has crush reliefs formed at both ends of an inner circumferential surface thereof in a circumferential direction, an oil groove formed on the inner circumferential surface thereof and extending in the circumferential direction, a central crown portion at substantially central position in the circumferential direction and in communication with the oil groove, and inflow preventing portions formed between the crush reliefs and the oil groove.