To provide a bearing device for a railroad vehicle capable of easily positioning an outer ring with respect to a housing and preventing the rotation thereof at low cost.

The bearing device for the railroad vehicle comprises an inner ring 3 fitted to an axle of the railroad vehicle, and an outer ring 1 arranged opposite to the outer side of the inner ring and fitted to a housing of the bearing device. The bearing device has a tool 29 to be interposed between housings H1, H2 and the outer ring. The tool has a tool body 29a to be fitted along the outer circumference of the outer ring, and a tool projecting part 29b projecting from the tool body toward the housing direction. While the tool body is fitted to the outer circumference of the outer ring, the tool projecting part is held by the housings to simultaneously position the outer ring to the housing and prevent the rotation. In place thereof, a projecting part is provided on the outer circumference of a seal case 25 for sealing the inside of the bearing, the projecting part is brought into contact with a rib structure of the housing when the bearing is rotated, and the rotation of the outer ring to the housing may be prevented thereby.