A wear-detection probe for a brake lining material comprises: a detection conductor which-extends a given length toward the rotor from the side of the brake lining material facing away from the rotor; a probe body housing supporting the detection conductor; a probe connector housing detachably connected to tile probe body housing; and a pair of terminals supported in the probe connector housing, the terminals contacting the detection conductor when the probe connector housing is connected to the probe body housing. The conductor either contacts the rotor or is cut off by the rotor when a predetermined thickness remains in the brake lining material due to wear. Since it is possible to exchange probes without exchanging harnesses, the cost for replacing the probe is greatly reduced.