To provide a roller bearing which is capable of sufficiently ensuring the durability of a roller even under a service condition where foreign matters are intruded and the temperature rise is high.

A steel, in which the content of Si and Mn is increased, is used for a material of each parts of an outer ring 1, an inner ring 2, and a conical roller 3, and the parts are carbonitrided, and hardened so that the residual austenite in carbonitrided layers 1a, 2a, 3a formed on a surface layer part of each parts is 20-50 vol.%. Generation of the surface separation attributable to generation and propagation of cracks is suppressed, and the durable service life of a roller bearing is remarkably improved even under a service condition where foreign matters are intruded and the heat generation is large at a bearing part.