To satisfactorily transmit a detecting signal indicating wheel rotation, from a wheel rotation sensor to the body side with a simple constitution.

A pair of conductors 31, 31 for transmitting a detecting signal indicating the rotation speed of a wheel, to the body BD side from a wheel rotation sensor 14 assembled to a hub carrier 11 for rotatably supporting a wheel W are bonded along a coil spring 22 disposed between the hub carrier 11 and the body BD. When the hub carrier 11 is displaced in relation to the body Bd, the conductors 31, 31 are expanded/contracted along with the coil spring 22, so that flexure of the conductors 31, 31 can be reduced to eliminate severance of wire or the like caused by interference of the conductors 31, 31 with other parts. It can also be so constituted that an outer spring and an inner spring formed of conductive elastic members are coaxial arranged to transmit the signal without using harness.