ROLLER BEARING AND RETAINER FOR ROLLER BEARING

A tapered roller bearing is provided which includes an inner ring (1) and an outer ring (2) both made of a steel material; and a plurality of cage segments (5) circumferentially continuously disposed between the inner ring (1) and the outer ring (2), into an annular shape. The cage segments (5) are made of a resin containing a predetermined amount of a predetermined thermally expandable filler, and having, in combination with the filler, a coefficient of linear expansion of less than 1.0 X 10-5/°C. A gap (R) is defined between the flat surfaces of the firstly mounted cage segment (5a) and the lastly mounted cage segment (5b). The amount by which the cage segments (5) thermally expand is limited such that, at the upper limit value of a bearing use temperature range, the gap (R) is less than 0.12% of the circumference of the circle passing through the centers of the annular cage segments in the radial thickness directions of the cage segments (5).