A comb-shaped resin retainer comprising: an annular section; and a plurality of pillar sections which protrude to one side in an axial direction from one side face of the annular section, wherein a gap between the pillar sections adjacent to each other in a circumferential direction serves as a pocket (Pt) for retaining a roller, and a side face of the pillar section, which serves as an inner face of the pocket (Pt), is formed in a recessed shape, wherein each of the pillar sections is tilted so as to become closer to a retainer axial center as the pillar section extends toward a tip of the pillar section, and a flat portion is provided on the side face of the pillar section which serves as the inner face of the pocket (Pt), and the flat portion continues axially from a tip portion of the pillar section toward a base end portion thereof, and the opposing flat portions of the pillar sections are in parallel to each other, wherein the flat portion of the pillar section is provided in a vicinity of a pitch circle diameter of the roller, characterised in that on the side face of the pillar section which serves as the inner face of the pocket (Pt), an outer diametric side recessed portion and an inner diametric side recessed portion are provided with the flat portion therebetween, and the outer diametric side recessed portion continues from an outer diametric side edge of the flat portion to an outer diametric side to form a portion of recessed side face of the pillar section which serves as the inner face of the pocket (Pt), while the inner diametric side recessed portion continues from an inner diametric side edge of the flat portion to an inner diametric side to form another portion of recessed side face of the pillar section which serves as the inner face of the pocket (Pt), and wherein a radius of curvature of the outer diametric side recessed portion is set larger than a radius of curvature of the inner diametric side recessed portion. an annular section; and a plurality of pillar sections which protrude to one side in an axial direction from one side face of the annular section, wherein a gap between the pillar sections adjacent to each other in a circumferential direction serves as a pocket (Pt) for retaining a roller, and a side face of the pillar section, which serves as an inner face of the pocket (Pt), is formed in a recessed shape, wherein each of the pillar sections is tilted so as to become closer to a retainer axial center as the pillar section extends toward a tip of the pillar section, and a flat portion is provided on the side face of the pillar section which serves as the inner face of the pocket (Pt), and the flat portion continues axially from a tip portion of the pillar section toward a base end portion thereof, and the opposing flat portions of the pillar sections are in parallel to each other, wherein the flat portion of the pillar section is provided in a vicinity of a pitch circle diameter of the roller, characterised in that on the side face of the pillar section which serves as the inner face of the pocket (Pt), an outer diametric side recessed portion and an inner diametric side recessed portion are provided with the flat portion therebetween, and the outer diametric side recessed portion continues from an outer diametric side edge of the flat portion to an outer diametric side to form a portion of recessed side face of the pillar section which serves as the inner face of the pocket (Pt), while the inner diametric side recessed portion continues from an inner diametric side edge of the flat portion to an inner diametric side to form another portion of recessed side face of the pillar section which serves as the inner face of the pocket (Pt), and wherein a radius of curvature of the outer diametric side recessed portion is set larger than a radius of curvature of the inner diametric side recessed portion.