A cylindrical roller bearing with an outer ring, comprising: an outer ring which includes: a cylindrical portion having an outer ring raceway surface on an inner circumferential surface thereof; an outward flange portion extending radially outward from an end portion on one side in an axial direction of the cylindrical portion; and an inward flange portion extending radially inward from an end portion on the other side in the axial direction of the cylindrical portion; a plurality of cylindrical rollers which are disposed rollably on the outer ring raceway surface; and a retainer which includes a pair of annular portions (31, 32) spaced apart in the axial direction, and a plurality of column portions connecting the pair of annular portions (31, 32) and arranged at intervals in a circumferential direction, and in which the plurality of cylindrical rollers are rollably held by a plurality of pockets each being formed by the column portions adjacent to each other and the pair of annular portions (31, 32), wherein: the annular portion on the other side in the axial direction is provided with a plurality of protrusion portions each having an engaging portion protruding radially outward with respect to an inner circumferential surface of the inward flange portion, characterized in that when an axial distance between a flat surface on the one side in the axial direction of the outward flange portion of the outer ring and an end surface on the one side in the axial direction of the annular portion of the retainer on the one side in the axial direction is set as A, and an axial distance between a flat surface on the other side in the axial direction of the inward flange portion of the outer ring and a side surface on the one side in the axial direction of the engaging portion of the retainer is set as B, B is greater than A. an outer ring which includes: a cylindrical portion having an outer ring raceway surface on an inner circumferential surface thereof; an outward flange portion extending radially outward from an end portion on one side in an axial direction of the cylindrical portion; and an inward flange portion extending radially inward from an end portion on the other side in the axial direction of the cylindrical portion; a cylindrical portion having an outer ring raceway surface on an inner circumferential surface thereof; an outward flange portion extending radially outward from an end portion on one side in an axial direction of the cylindrical portion; and an inward flange portion extending radially inward from an end portion on the other side in the axial direction of the cylindrical portion; a plurality of cylindrical rollers which are disposed rollably on the outer ring raceway surface; and a retainer which includes a pair of annular portions (31, 32) spaced apart in the axial direction, and a plurality of column portions connecting the pair of annular portions (31, 32) and arranged at intervals in a circumferential direction, and in which the plurality of cylindrical rollers are rollably held by a plurality of pockets each being formed by the column portions adjacent to each other and the pair of annular portions (31, 32), wherein: the annular portion on the other side in the axial direction is provided with a plurality of protrusion portions each having an engaging portion protruding radially outward with respect to an inner circumferential surface of the inward flange portion, characterized in that when an axial distance between a flat surface on the one side in the axial direction of the outward flange portion of the outer ring and an end surface on the one side in the axial direction of the annular portion of the retainer on the one side in the axial direction is set as A, and an axial distance between a flat surface on the other side in the axial direction of the inward flange portion of the outer ring and a side surface on the one side in the axial direction of the engaging portion of the retainer is set as B, B is greater than A. the annular portion on the other side in the axial direction is provided with a plurality of protrusion portions each having an engaging portion protruding radially outward with respect to an inner circumferential surface of the inward flange portion, characterized in that when an axial distance between a flat surface on the one side in the axial direction of the outward flange portion of the outer ring and an end surface on the one side in the axial direction of the annular portion of the retainer on the one side in the axial direction is set as A, and an axial distance between a flat surface on the other side in the axial direction of the inward flange portion of the outer ring and a side surface on the one side in the axial direction of the engaging portion of the retainer is set as B, B is greater than A.