A cage of a roller bearing comprising: a pair of rings and a plurality of pillars that couple the rings and extend in the axial direction so as to form pockets to accommodate the rollers, wherein each of the pillars includes a radially outer projection that is formed at the radially outer side of a pillar's wall surface facing a pocket so as to project in the circumference direction and restricts radially outward movement of a roller and a radially inner projection that is formed at the radially inner side of the pillar's wall surface facing the pocket so as to project in the circumference direction and restricts radially inward movement of the roller, wherein the radially outer projection has an end rounded into an arc shape in cross section and wherein the outer projection has an inner inclined surface being inclined with an inclination angle (α) between 15° and 25° (15° < α < 25°) relative to a reference plane containing an axis of the cage and passing through the circumferential center of the pocket and being smaller than an inclination angle (β) of an inclined surface on a radially outer side of the radially inner projection, and allowable distance Lo to which the roller can move radially outward from a pitch circle of the rollers under the restriction of the radially outer projections and allowable distance Li to which the roller can move radially inward from the pitch circle of the rollers under the restriction of the radially inner projections satisfy the relationship Lo>Li, wherein distance Bo between the radially outer projections facing each other with a pocket interposed therebetween and distance Bi between the radially inner projections facing each other with the pocket interposed therebetween satisfy the relationship Bo>Bi. a pair of rings and a plurality of pillars that couple the rings and extend in the axial direction so as to form pockets to accommodate the rollers, wherein each of the pillars includes a radially outer projection that is formed at the radially outer side of a pillar's wall surface facing a pocket so as to project in the circumference direction and restricts radially outward movement of a roller and a radially inner projection that is formed at the radially inner side of the pillar's wall surface facing the pocket so as to project in the circumference direction and restricts radially inward movement of the roller, wherein the radially outer projection has an end rounded into an arc shape in cross section and wherein the outer projection has an inner inclined surface being inclined with an inclination angle (α) between 15° and 25° (15° < α < 25°) relative to a reference plane containing an axis of the cage and passing through the circumferential center of the pocket and being smaller than an inclination angle (β) of an inclined surface on a radially outer side of the radially inner projection, and allowable distance Lo to which the roller can move radially outward from a pitch circle of the rollers under the restriction of the radially outer projections and allowable distance Li to which the roller can move radially inward from the pitch circle of the rollers under the restriction of the radially inner projections satisfy the relationship Lo>Li, wherein distance Bo between the radially outer projections facing each other with a pocket interposed therebetween and distance Bi between the radially inner projections facing each other with the pocket interposed therebetween satisfy the relationship Bo>Bi.