A compressor comprising: a rotary shaft that is configured to rotate about a center axis; an impeller that is fixed to the rotary shaft and that is configured to compress a working fluid by integrally rotating with the rotary shaft; a casing that covers the rotary shaft; a first seal portion that is disposed at a position away from the impeller in a center axis direction of the rotary shaft and that is configured to seal a portion between the rotary shaft and the casing with a seal gas; a second seal portion (60,60B) that is disposed between the impeller and the first seal portion and that is configured to seal a portion between the rotary shaft and the casing; a gas supply path (100, 100B) through which the seal gas is introduced into the first seal portion; and a gas outflow path that is provided in the second seal portion (60,60B) and communicates with a pressure space having a pressure lower than that of the seal gas to allow at least some of the seal gas to flow out from the first seal portion to the pressure space, wherein the gas supply path (100, 100B) is connected to a working fluid flow path, in which the working fluid flows, at a supply side connecting portion and allows the working fluid, which is the seal gas, to be introduced into the first seal portion, and the gas outflow path is connected to the working fluid flow path at a position where a pressure of the flowing working fluid is lower than that of the supply side connecting portion, and wherein the impeller includes a first impeller and a second impeller that is configured to compress the working fluid compressed by the first impeller, characterized in that the gas supply path (100, 100b) communicates with the working fluid flow path at a position where the working fluid compressed by the first impeller flows. a rotary shaft that is configured to rotate about a center axis; an impeller that is fixed to the rotary shaft and that is configured to compress a working fluid by integrally rotating with the rotary shaft; a casing that covers the rotary shaft; a first seal portion that is disposed at a position away from the impeller in a center axis direction of the rotary shaft and that is configured to seal a portion between the rotary shaft and the casing with a seal gas; a second seal portion (60,60B) that is disposed between the impeller and the first seal portion and that is configured to seal a portion between the rotary shaft and the casing; a gas supply path (100, 100B) through which the seal gas is introduced into the first seal portion; and a gas outflow path that is provided in the second seal portion (60,60B) and communicates with a pressure space having a pressure lower than that of the seal gas to allow at least some of the seal gas to flow out from the first seal portion to the pressure space, wherein the gas supply path (100, 100B) is connected to a working fluid flow path, in which the working fluid flows, at a supply side connecting portion and allows the working fluid, which is the seal gas, to be introduced into the first seal portion, and the gas outflow path is connected to the working fluid flow path at a position where a pressure of the flowing working fluid is lower than that of the supply side connecting portion, and wherein the impeller includes a first impeller and a second impeller that is configured to compress the working fluid compressed by the first impeller, characterized in that the gas supply path (100, 100b) communicates with the working fluid flow path at a position where the working fluid compressed by the first impeller flows.