Abstract: A tapered roller bearing for a pinion shaft according to the invention includes an inner ring that has an outer circumferential surface on which an inner ring raceway surface is formed and that is integrally fixed to a one-end-side of the pinion shaft, an outer ring that has an inner circumferential surface on which an outer ring raceway surface is formed and that is fixed to a housing, and a plurality of tapered rollers rollably interposed between both of the raceway surfaces. An annular oil reservoir groove for storing lubricating oil is formed in a distal end portion at the one-end-side in an axial direction of the inner circumferential surface by being recessed thereinto adjacent to the outer ring raceway surface.