Abstract: An AE-signal detecting device for an abrasive wheel includes: an AE sensor which outputs an AE signal upon receipt of an elastic wave generated in an annular abrasive wheel sandwiched between a fixed flange fixed to a rotating shaft and a movable flange provided capable of getting closer to/separating from the fixed flange; a transmission circuit portion which wirelessly transmits the AE signal output from the AE sensor; and a reception circuit portion which receives the AE signal transmitted wirelessly, wherein the AE sensor is disposed on the movable flange or the fixed flange, detects the elastic wave transmitted from the abrasive wheel, and outputs the AE signal.