To allow maximum extension of life by equalizing, with in-bearing design, load sharing of rollers of central two trains which tend to rise as compared with those of two trains on both sides due to rigidity of housing and load point position of housing (contacting state of pressure receiving surface).

Four roller trains, A-D trains, are provided between an inner ring 3 and outer rings 6-9. The bearing radial gaps Δr of central two roller trains, B and C trains, are set identical among four roller trains. The bearing radial gaps of two side roller trains, A and D trains, positioned on both sides of the central two trains are set identical. The bearing radial gaps of the central two roller trains, B and C trains, are set higher than the bearing radial gaps of two side roller trains, A and D trains. Further, a means for regulating order of incorporating four roller trains is provided.