To provide a bearing device capable of accurately calculating the pre-load applied to a bearing without using an electrical contact such as a brush or a slip ring and without being influenced by a bearing temperature or the rotating speed of a spindle.

A spacer is interposed between race rings of rolling bearings 3A and 3B arranged side by side in an axial direction, and the pre-load is applied to the rolling bearings. A first electrode 11 is electrically connected to a fixed ring 3g of the rolling bearing. A second electrode 12 is provided on a member 8 in a fixed state with respect to the fixed ring 3g so as to be electrically insulated. An electrostatic capacity generation part 18 is formed between the second electrode 12 and a rotating ring 3i of the rolling bearing. The electrostatic capacity between the electrodes 11 and 12 is measured by an electrostatic capacity measurement means 19, and the bearing pre-load is detected by a pre-load detecting means 20 based on the measured value. Temperature sensors 22 and 23 for measuring the bearing temperature are disposed on the spacer 5 of the fixed ring 3g, and the pre-load detected by the pre-load detecting means 20 is corrected by a correcting means based on the measured bearing temperature.

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