A roller bearing has spacers interposed between its rollers. The roller bearing also has a high permissible rotational speed which is achieved by allowing a lubricant to flow smoothly around rolling surfaces so that the stirring resistance of the lubricant due to the spacers is reduced. The roller bearing includes a plurality of rotatable rollers interposed between an inner ring raceway surface and an outer ring raceway surface and spacers provided between adjacent rollers. Each of the spacers includes extended portions facing roller end faces of the rollers at both axial ends thereof.