A compressor, comprising: a guide casing housing an impeller wheel for compressing an intake fluid, and being configured to guide the intake fluid; a scroll-chamber frame forming a scroll-chamber for guiding the intake fluid having passed through the guide casing to the outside, the scroll-chamber frame further comprising: a scroll-chamber inner forming part disposed outside the guide casing in a radial direction of a rotational axis of the impeller wheel, and forming an inner peripheral wall surface of the scroll chamber; a scroll-chamber outer forming part forming an outer peripheral wall surface of the scroll chamber; and a cylindrical support part disposed outside the guide casing in the radial direction and inside the scroll-chamber inner forming part in the radial direction, the cylindrical support part of a cylindrical shape having the same central axis as the rotational axis of the impeller wheel; wherein the scroll-chamber inner forming part and the guide casing are connected to each other via the cylindrical support part, and wherein the scroll-chamber inner forming part and the scroll-chamber outer forming part are fastened to each other by a bolt at a flange portion, and a silencer configured to reduce noise, wherein the silencer and the scroll-chamber frame are fastened to each other at a flange portion of the silencer and the flange portion of the scroll-chamber frame by the bolt, and characterized in that the compressor further comprises: a plurality of first ribs extending on an outer side with respect to the radial direction of the cylindrical support from the rotational axis S, and connected to the scroll-chamber inner forming part, and a second rib extending on an outer side with respect to the radial direction of the guide casing, and being disposed in a region surrounded by the cylindrical support part and the guide casing. a guide casing housing an impeller wheel for compressing an intake fluid, and being configured to guide the intake fluid; a scroll-chamber frame forming a scroll-chamber for guiding the intake fluid having passed through the guide casing to the outside, the scroll-chamber frame further comprising: a scroll-chamber inner forming part disposed outside the guide casing in a radial direction of a rotational axis of the impeller wheel, and forming an inner peripheral wall surface of the scroll chamber; a scroll-chamber outer forming part forming an outer peripheral wall surface of the scroll chamber; and a cylindrical support part disposed outside the guide casing in the radial direction and inside the scroll-chamber inner forming part in the radial direction, the cylindrical support part of a cylindrical shape having the same central axis as the rotational axis of the impeller wheel; a scroll-chamber inner forming part disposed outside the guide casing in a radial direction of a rotational axis of the impeller wheel, and forming an inner peripheral wall surface of the scroll chamber; a scroll-chamber outer forming part forming an outer peripheral wall surface of the scroll chamber; and a cylindrical support part disposed outside the guide casing in the radial direction and inside the scroll-chamber inner forming part in the radial direction, the cylindrical support part of a cylindrical shape having the same central axis as the rotational axis of the impeller wheel; wherein the scroll-chamber inner forming part and the guide casing are connected to each other via the cylindrical support part, and wherein the scroll-chamber inner forming part and the scroll-chamber outer forming part are fastened to each other by a bolt at a flange portion, and a silencer configured to reduce noise, wherein the silencer and the scroll-chamber frame are fastened to each other at a flange portion of the silencer and the flange portion of the scroll-chamber frame by the bolt, and characterized in that the compressor further comprises: a plurality of first ribs extending on an outer side with respect to the radial direction of the cylindrical support from the rotational axis S, and connected to the scroll-chamber inner forming part, and a second rib extending on an outer side with respect to the radial direction of the guide casing, and being disposed in a region surrounded by the cylindrical support part and the guide casing. a plurality of first ribs extending on an outer side with respect to the radial direction of the cylindrical support from the rotational axis S, and connected to the scroll-chamber inner forming part, and a second rib extending on an outer side with respect to the radial direction of the guide casing, and being disposed in a region surrounded by the cylindrical support part and the guide casing.