The present invention provides a wheel bearing with sensor capable of compactly mounting on a vehicle, capable of sensitively detecting a load on a wheel, and the cost at the mass production can be lowered. The wheel bearing provided with the rotation body 3 of a double raw intervened between the external member 1 and the internal member 2, is provided with the sensor unit 21. The sensor unit 21 is composed of the ring member 21 attached to the internal circumference of the external member 1 or a sensor fixing member, the strain sensor 23 for measuring the strain of the member and the magnetic sensor 24 for detecting the rotation. The internal member 2 of rotational side member is provided with the magnetic body of to be detected part 25 opposite to the magnetic sensor 24. If the internalmember 2 is a stationary member, the sensor unit 21 provided with the strain sensor 23 and the magnetic sensor 24 is fixed on the internal member 2 and the detection part 25 is provided on the external member 1.