A capacitive sensor for measuring the clearance between the apex of the vanes of a rotor and the inner surface of an abradable coating covering the inner surface of a turbomachine casing, the clearance measuring capacitive sensor including a first electrode the material of which is abradable so as to get worn upon contacting an apex of a vane, the material of the first electrode having a degree of wear substantially identical to the degree of wear of the material of the abradable coating.