A roller bearing cage is made of a resin and has a tapered tubular shape as a whole. In the roller bearing cage, tapered rollers are forcibly fitted to pockets while elastically deforming pillar portions at a small-diameter annular portion side. A stress alleviating portion is provided on at least an outer circumferential side of an end of the pillar portion at the small-diameter annular portion side so that a portion of the pillar portion from a crossing portion between the pillar portion and the small-diameter annular portion to a side of the large-diameter annular portion is linearly cut, thereby alleviating the stress occurring in the pillar portion when the tapered roller is forcibly fitted to the pocket.