A conveyer belt abrasion detecting apparatus which can automatically detect a conveyer belt abrasion quantity easily and accurately during operation. A plurality of magnet sheets (M1-M5) magnetized in a thickness direction are arranged so that polarities on the surface are in the same direction and are embedded deeper stepwise in a longitudinal direction of a belt main body (2). A magnetic sensor (4) for detecting changes of the magnetic forces of the magnet sheets (M1-M5) is arranged at a position where the magnet sheets (M1-M5) pass through.