A conveyor belt wear detection apparatus, comprising: a rubber magnet embedded in a conveyor belt (2, 30); a magnetic sensor which is disposed in proximity to a front-side surface (2a, 30a) forming an outer peripheral surface of the conveyor belt (2, 30) and detects a magnetic field from the rubber magnet; and an arithmetic section (20, 33) comprising a control unit for receiving a signal from the magnetic sensor and for estimating, based on the signal from the magnetic sensor, a wear amount on the front-side surface (2a, 30a) of the conveyor belt (2, 30), wherein the rubber magnet extends in a conveyor belt width direction and includes a diagonal portion in a plate shape and a parallel portion in a plate shape which are both magnetized in a thickness direction, the diagonal portion linearly extending, in section in a conveyor belt length direction, from an outer side end, which is closer to the front-side surface (2a, 30a), to an inner side end, which is away from the front-side surface (2a, 30a), while being at an angle to the front-side surface (2a, 30a), the parallel portion being arranged parallel to the front-side surface (2a, 30a), characterised in that the parallel portion is formed continuously from the inner side end of the diagonal portion; wherein the arithmetic section (20, 33) estimates a wear amount of the conveyor belt (2, 30) upon detection of a magnetic field, based on a ratio (Rx/R0) of a waveform width Rx to an initial waveform width R0, in which the waveform width Rx is obtained, in a time variation pattern of a magnetic field detected by the magnetic sensor, at a threshold value predetermined as a specific sensor output value and the initial waveform width R0 is obtained at the threshold value in a time variation pattern detected for the conveyor belt (2, 30) that has not been subjected to wear. a rubber magnet embedded in a conveyor belt (2, 30); a magnetic sensor which is disposed in proximity to a front-side surface (2a, 30a) forming an outer peripheral surface of the conveyor belt (2, 30) and detects a magnetic field from the rubber magnet; and an arithmetic section (20, 33) comprising a control unit for receiving a signal from the magnetic sensor and for estimating, based on the signal from the magnetic sensor, a wear amount on the front-side surface (2a, 30a) of the conveyor belt (2, 30), wherein the rubber magnet extends in a conveyor belt width direction and includes a diagonal portion in a plate shape and a parallel portion in a plate shape which are both magnetized in a thickness direction, the diagonal portion linearly extending, in section in a conveyor belt length direction, from an outer side end, which is closer to the front-side surface (2a, 30a), to an inner side end, which is away from the front-side surface (2a, 30a), while being at an angle to the front-side surface (2a, 30a), the parallel portion being arranged parallel to the front-side surface (2a, 30a), characterised in that the parallel portion is formed continuously from the inner side end of the diagonal portion; wherein the arithmetic section (20, 33) estimates a wear amount of the conveyor belt (2, 30) upon detection of a magnetic field, based on a ratio (Rx/R0) of a waveform width Rx to an initial waveform width R0, in which the waveform width Rx is obtained, in a time variation pattern of a magnetic field detected by the magnetic sensor, at a threshold value predetermined as a specific sensor output value and the initial waveform width R0 is obtained at the threshold value in a time variation pattern detected for the conveyor belt (2, 30) that has not been subjected to wear.