The thickness of a crossed roller bearing is reduced and attachment of a lid member 17 to a loading hole 16 from which rollers 15 are loaded is facilitated. Raceway grooves 13, 14 are respectively formed in an inner ring 11 and an outer ring 12. The rollers are loaded from the loading hole formed in the outer ring, and interposed between the raceway grooves. The axes of the adjacent rollers lie at right angles to each other. The loading hole is covered by the lid member. A flange 22 is provided on an outer periphery of the outer ring, and has an outer end face 22a that is approximately flush with an end face of the outer ring and an inner end face 22b that is either in a position in alignment with or in an inner position across outer ends of the raceway grooves in an axial direction.