A fixing component for a switch comprising: a flange; a ring attachment; and a screw attachment having a screw structure to be screwed in the ring attachment, the switch being attached to an attachment panel by sandwiching an edge of a mounting hole of the attachment panel between the flange and the screw attachment, and the flange comprising a projection, and the screw attachment comprising an insertion area into which the projection of the flange is inserted, a projection engaging part into which the projection of the flange is fitted, characterized in that:. the projection is provided on an outer peripheral surface having a circular cross section of the flange,. the insertion area is provided on an inner peripheral surface having a circular crosection of the screw attachment,. an interference projection is formed between the projection engaging part and the insertion area and has a smaller inner diameter than diameters of the projection engaging part and the insertion area,. the projection of the flange comprises a first projecting portion extending along an outer peripheral surface in a circumferential direction and a second projecting portion extending in a direction perpendicular to the circumferential direction, and. the projection engaging part is formed by a guiding groove and a fitting groove, and. the first projecting portion is fitted into the guiding groove, and the second projecting portion is configured to traverse over the interference projection to be fitted into the fitting groove when the flange and the screw attachment are rotated relatively in one predetermined circumferential direction. a flange; a ring attachment; and a screw attachment having a screw structure to be screwed in the ring attachment, the switch being attached to an attachment panel by sandwiching an edge of a mounting hole of the attachment panel between the flange and the screw attachment, and the flange comprising a projection, and the screw attachment comprising an insertion area into which the projection of the flange is inserted, a projection engaging part into which the projection of the flange is fitted,. the projection is provided on an outer peripheral surface having a circular cross section of the flange,. the insertion area is provided on an inner peripheral surface having a circular crosection of the screw attachment,. an interference projection is formed between the projection engaging part and the insertion area and has a smaller inner diameter than diameters of the projection engaging part and the insertion area,. the projection of the flange comprises a first projecting portion extending along an outer peripheral surface in a circumferential direction and a second projecting portion extending in a direction perpendicular to the circumferential direction, and. the projection engaging part is formed by a guiding groove and a fitting groove, and. the first projecting portion is fitted into the guiding groove, and the second projecting portion is configured to traverse over the interference projection to be fitted into the fitting groove when the flange and the screw attachment are rotated relatively in one predetermined circumferential direction.