To provide a bearing device having simple construction preventing an unnecessary slip inside bearings when a fixed-position preload escapes.

A spindle 3 of a machine tool is installed on a housing 2 via the load-side bearing 5A and the counter-load-side bearing 5B. Both bearings 5A, 5B are angular ball bearings arranged back to back. The load-side bearing 5A has an outer ring 11A which is positioned and fixed onto the housing 2 in the axial direction, and the counter-load-side bearing 5B has an outer ring 11B which is not positioned and fixed to the housing 2 in the axial direction. The axial positions of inner rings 12A, 12B of both bearings 5A, 5B are restricted to give the fixed-position preload to both bearings 5A, 5B. Between the back face of the outer ring 11B of the counter-load-side bearing 5B and the housing 2, an elastic body 10 is laid for energizing the outer ring 11B of the counter-load-side bearing 5B to the front-face side.