To provide a bearing device having improved distortion detecting sensitivity for measuring preload on a bearing in a well sensitive manner.

On part of a spacer in the axial direction, a ring-shaped distortion producing member 7 is provided for producing distortion with axial force on the spacer between both ends. The distortion producing member 7 includes distortion producing body parts 11 which each have a distortion producing portion 11ca easier to elastically deform than the other position, and load applying body parts 10 which are each integrally provided at one axial end of the distortion producing body part 11 for applying a load onto the distortion producing portion 11ca, at a plurality of circumferential positions.