A centrifugal compressor comprising: an impeller; and a casing accommodating the impeller, wherein the casing includes: an inlet; an impeller-accommodating portion, the impeller being disposed in the impeller-accommodating portion; an annular flow passageway formed around the impeller; an outlet communicating with the annular flow passageway; an annular chamber formed around the inlet; a downstream groove communicating a downstream end portion of the annular chamber with the impeller-accommodating portion; and an upstream groove communicating an upstream end portion of the annular chamber to the inlet; the downstream groove is opened and provided in a predetermined range in a circumferential direction of the impeller so as to communicate with a high-pressure part that occurs in part of the impeller-accommodating portion, the upstream groove is provided over an entire circumference of the inlet, and characterized in that a tongue portion is formed between the outlet and the annular flow passageway, and the downstream groove is only formed in a range from a position of 45° upsteam with respect to a reference radial line connecting a rotation center of the impeller and the tongue portion, to a portion of 75° downstream with respect to the reference radial line. an impeller; and a casing accommodating the impeller, wherein the casing includes: an inlet; an impeller-accommodating portion, the impeller being disposed in the impeller-accommodating portion; an annular flow passageway formed around the impeller; an outlet communicating with the annular flow passageway; an annular chamber formed around the inlet; a downstream groove communicating a downstream end portion of the annular chamber with the impeller-accommodating portion; and an upstream groove communicating an upstream end portion of the annular chamber to the inlet; the downstream groove is opened and provided in a predetermined range in a circumferential direction of the impeller so as to communicate with a high-pressure part that occurs in part of the impeller-accommodating portion, an inlet; an impeller-accommodating portion, the impeller being disposed in the impeller-accommodating portion; an annular flow passageway formed around the impeller; an outlet communicating with the annular flow passageway; an annular chamber formed around the inlet; a downstream groove communicating a downstream end portion of the annular chamber with the impeller-accommodating portion; and an upstream groove communicating an upstream end portion of the annular chamber to the inlet; the downstream groove is opened and provided in a predetermined range in a circumferential direction of the impeller so as to communicate with a high-pressure part that occurs in part of the impeller-accommodating portion, the upstream groove is provided over an entire circumference of the inlet, and characterized in that a tongue portion is formed between the outlet and the annular flow passageway, and the downstream groove is only formed in a range from a position of 45° upsteam with respect to a reference radial line connecting a rotation center of the impeller and the tongue portion, to a portion of 75° downstream with respect to the reference radial line.