A flange part of an inner ring member (11) used in a roller bearing has a thin-wall part (13) having a relatively small diameter direction thickness on its end face side, and a thick-wall part (14) having a relatively large diameter direction thickness on its center side, and an inner diameter surface has a contact part (15) fitted to a shaft at its center part, a non-contact part (16) apart from the shaft in a diameter direction at its outer edge, and a ridge line part (17) positioned on the boundary between the contact part (15) and the non-contact part (16). The axial direction width L 1 of the thin-wall part (13) from an end face (12) of the inner ring member (11) and the axial direction distance L 2 between the end face (12) and a ridge line part (17) of the inner ring member (11) have a relation of L 1 > L 2 .