Abstract: A rotary body fixing device capable of mounting and removing a rotary body on a shaft easily and rapidly. The device has inner and outer elastically deformable rings and a pair of oppositely tapered rings for wedging between the inner and outer rings in a clamping position. Extraction bolt holes 4F for threaded engagement with extraction bolts 7 are formed axially through one tapered ring 4. The extraction bolts 7 come into abutment at their tip ends against an end face of the other tapered ring 5 to move both tapered rings away from each other. In an axially medial part of the outer peripheral surface of the inner ring 2 and of the inner peripheral surface of the outer ring 3, annular grooves respectively form stepped portions on both sides of the annular groove.