To provide a fixing device capable of supporting easily and quickly fixing a fitting object member, and to provide fixing device for a roller device.

The support 6 of the motor incorporated roller 1 is fixed to a side wall part 17a via a fitting plate 19. A lock shaft part 14 of the support 6 is inserted into an insertion hole 21 of the fitting plate 19, and the relative rotation of the support 6 to the fitting plate 19 is impeded. A nut 22 is fastened around a screw shaft part 15 of the support 6, and the fitting plate 19 is pushed against the sidewall part 17a, so that a claw 20 is caught by the surface of the sidewall part 17a and prevent the fitting plate 19 from relatively rotating with respect to the sidewall part 17a. The supports 6 and 7 are thus fixed incapable of rotation relative to the sidewall part 17a.