To provide a bearing apparatus with a sensor capable of reliably detecting the state of a bearing by the sensor for a long period.

The bearing (10a) comprises a pair of bearing rings relatively rotated via a rotator (13), and a ring-shaped housing part (20) adjacent to a bearing space is provided for at least one side of the axial direction of the bearing (10a). The housing part (20) is surrounded with both a tone ring (28) fixed to one of the bearing rings to be a turning ring and a ring-shaped yoke member (21) fixed to the other bearing ring to be a stationary ring. The yoke member (21) is provided with a pole piece (22) in such a way as to oppose the tone ring (28) in a radial direction to form a magnetic circuit. The pole piece (22) comprises both a permanent magnet (22a) and a coil (22c) wound on the outer circumference of the permanent magnet (22a) or a magnetic body (22b) fixed to the permanent magnet (22a). The sensor for detecting the state of the bearing (10a) is housed in the housing part (20). Electric power generated in the pole piece (22) with the rotation of the tone ring (28) is supplied for the sensor to detect rotating speed and at least one of temperature, vibration, pressure, and humidity.