A roller bearing cage for rotatably holding, at a predetermined interval, rollers (15A; 15B) serving as rolling elements of a roller bearing, the roller bearing cage being provided with a plurality of pocket holes at equal intervals in a circumferential direction for housing the rollers (15A; 15B), wherein a plurality of columns connect a pair of rings (11, 12) that are apart from each other in an axial direction, each of the columns, which is positioned between the pocket holes adjacent to each other, includes: a center guide portion for guiding the rollers (15A; 15B), the center guide portion being positioned at an axially center of the column in a radially outside of a pitch circle diameter of the rollers (15A; 15B); and a pair of end portions (6, 7) each of which is connected to the center guide portion at one end and to a corresponding one of the rings (11, 12) at the other end in the radially outside of the center guide portion, each of the end portions of the column has a retaining projection so that the retaining projection is positioned, in each of the pocket holes, diagonally opposite to another retaining projection, characterized in that: an axial-direction relief portion is provided, in each of the pocket holes, diagonally opposite to another axial-direction relief portion in a corner of the pocket hole where the retaining projection is provided, and a circumferential-direction relief portion is provided, in each of the pocket holes, diagonally opposite to another circumferential-direction relief portion in a corner of the pocket hole where no retaining projection is provided. a plurality of columns connect a pair of rings (11, 12) that are apart from each other in an axial direction, each of the columns, which is positioned between the pocket holes adjacent to each other, includes: a center guide portion for guiding the rollers (15A; 15B), the center guide portion being positioned at an axially center of the column in a radially outside of a pitch circle diameter of the rollers (15A; 15B); and a pair of end portions (6, 7) each of which is connected to the center guide portion at one end and to a corresponding one of the rings (11, 12) at the other end in the radially outside of the center guide portion, a center guide portion for guiding the rollers (15A; 15B), the center guide portion being positioned at an axially center of the column in a radially outside of a pitch circle diameter of the rollers (15A; 15B); and a pair of end portions (6, 7) each of which is connected to the center guide portion at one end and to a corresponding one of the rings (11, 12) at the other end in the radially outside of the center guide portion, each of the end portions of the column has a retaining projection so that the retaining projection is positioned, in each of the pocket holes, diagonally opposite to another retaining projection, characterized in that: an axial-direction relief portion is provided, in each of the pocket holes, diagonally opposite to another axial-direction relief portion in a corner of the pocket hole where the retaining projection is provided, and a circumferential-direction relief portion is provided, in each of the pocket holes, diagonally opposite to another circumferential-direction relief portion in a corner of the pocket hole where no retaining projection is provided. an axial-direction relief portion is provided, in each of the pocket holes, diagonally opposite to another axial-direction relief portion in a corner of the pocket hole where the retaining projection is provided, and a circumferential-direction relief portion is provided, in each of the pocket holes, diagonally opposite to another circumferential-direction relief portion in a corner of the pocket hole where no retaining projection is provided.