A compressor comprising: a rotor having a rotary shaft which is configured to rotate around an axis, and an impeller provided integrally with the rotary shaft ; a casing having a casing main body which surrounds the rotor and forms an annular inlet flow path (F1) surrounding the axis at a front stage of the impeller , and an inlet nozzle which is configured to introduce a fluid into the inlet flow path (F1) from an outer side in a radial direction; an external pipe connected to the inlet nozzle to introduce the fluid from an outside of the compressor to the inlet nozzle ; and a cleaning liquid supply part which is configured to supply a cleaning liquid from a plurality of locations in a circumferential direction of the external pipe to an interior of the external pipe , said compressor being characterized in that the inlet nozzle is formed such that a cross-sectional area, when viewed from the radial direction, gradually decreases from the outer side toward an inner side in the radial direction, and in that the external pipe includes: a straight pipe part which is directly connected to the inlet nozzle and extends to form a flow path which is linear with respect to the inlet nozzle , and a curved part which is connected to the straight pipe part on a side opposite to the inlet nozzle and forms a curved flow path, wherein the straight pipe part is a cylindrical pipe having the same diameter over the entire area in an extending direction thereof, and the cleaning liquid supply part is provided in the straight pipe part . a rotor having a rotary shaft which is configured to rotate around an axis, and an impeller provided integrally with the rotary shaft ; a casing having a casing main body which surrounds the rotor and forms an annular inlet flow path (F1) surrounding the axis at a front stage of the impeller , and an inlet nozzle which is configured to introduce a fluid into the inlet flow path (F1) from an outer side in a radial direction; an external pipe connected to the inlet nozzle to introduce the fluid from an outside of the compressor to the inlet nozzle ; and a cleaning liquid supply part which is configured to supply a cleaning liquid from a plurality of locations in a circumferential direction of the external pipe to an interior of the external pipe , said compressor being characterized in that the inlet nozzle is formed such that a cross-sectional area, when viewed from the radial direction, gradually decreases from the outer side toward an inner side in the radial direction, and in that the external pipe includes: a straight pipe part which is directly connected to the inlet nozzle and extends to form a flow path which is linear with respect to the inlet nozzle , and a curved part which is connected to the straight pipe part on a side opposite to the inlet nozzle and forms a curved flow path, wherein the straight pipe part is a cylindrical pipe having the same diameter over the entire area in an extending direction thereof, and the cleaning liquid supply part is provided in the straight pipe part . a straight pipe part which is directly connected to the inlet nozzle and extends to form a flow path which is linear with respect to the inlet nozzle , and a curved part which is connected to the straight pipe part on a side opposite to the inlet nozzle and forms a curved flow path, wherein the straight pipe part is a cylindrical pipe having the same diameter over the entire area in an extending direction thereof, and the cleaning liquid supply part is provided in the straight pipe part . <EOS>