To provide a roller bearing with a sensor capable of detecting the load activating on the roller bearing without arranging sensors on a plurality of positions.

The sensor 2 is provided with the excitation coil 7, the closed magnetic circuit 10 of which is coaxially with the stationary tracking member 3 and fixed with the same formed by the stationary track member 3, the rotary body 5A of either lane, the rotary track member 4, the rotary body 5B of other lane and the stationary track member 3; the AC source 31 for supplying AC current to the excitation coil 7; the detection coil 8 in which the current flows corresponding to the total area of the contact area of the rotary bodies of the magnetic closed circuit 10 varying depending on the current flowing in the coil 7 and the load; the measuring means 32 for detecting the induction current generated in the detection coil 8; and the processing means 11 for obtaining lateral G acing to the hub unit 1 as the roller bearing from the output of the measuring means 32.