A rotary machine comprising a rotor which is rotatable around a rotational axis, the rotor including a cooling target to be cooled by a thermosiphon action, the rotary machine further comprising: a condenser section which is disposed outside the rotor and provided for condensing gas phase cooling medium into a liquid phase cooling medium; an evaporator section which is disposed inside the rotor, and provided for evaporating the liquid phase cooling medium generated by condensation in the condenser section into the gas phase cooling medium, by heat exchange between the cooling target and the liquid phase cooling medium; and a coupling pipe which flows therethrough the liquid phase cooling medium and the gas phase cooling medium between the evaporator section and the condenser section, and has a bent portion, wherein the coupling pipe includes: a liquid phase cooling medium passage which flows therethrough the liquid phase cooling medium generated by the condensation in the condenser section; and a gas phase cooling medium passage which flows therethrough the gas phase cooling medium generated by evaporation in the evaporator section, the liquid phase cooling medium passage and the gas phase cooling medium passage being separately provided, wherein the coupling pipe has a double pipe structure in which an inner pipe is the gas phase cooling medium passage, and a space formed between the inner pipe and an outer pipe surrounding an outer periphery of the inner pipe is the liquid phase cooling medium passage, and wherein the coupling pipe has a shape in which a first end portion of the coupling pipe is inserted into the evaporator section, the coupling pipe extends from the evaporator section toward an outside region of the rotor along the rotational axis, and a second end portion of the coupling pipe is secured to the condenser section, the coupling pipe is configured such that the liquid phase cooling medium flows through the liquid phase cooling medium passage by utilizing a gravitational force, characterized in that the double pipe structure extends over the entirety of the coupling pipe including the bent portion, inside the evaporator section, a first end portion of the gas phase cooling medium passage, which is closer to the evaporator section, protrudes more than a first end portion of the liquid phase cooling medium passage, which is closer to the evaporator section, and an ingress prevention section is provided inside the condenser section and for preventing ingress of the liquid phase cooling medium into the gas phase cooling medium passage. a condenser section which is disposed outside the rotor and provided for condensing gas phase cooling medium into a liquid phase cooling medium; an evaporator section which is disposed inside the rotor, and provided for evaporating the liquid phase cooling medium generated by condensation in the condenser section into the gas phase cooling medium, by heat exchange between the cooling target and the liquid phase cooling medium; and a coupling pipe which flows therethrough the liquid phase cooling medium and the gas phase cooling medium between the evaporator section and the condenser section, and has a bent portion, wherein the coupling pipe includes: a liquid phase cooling medium passage which flows therethrough the liquid phase cooling medium generated by the condensation in the condenser section; and a gas phase cooling medium passage which flows therethrough the gas phase cooling medium generated by evaporation in the evaporator section, the liquid phase cooling medium passage and the gas phase cooling medium passage being separately provided, wherein the coupling pipe has a double pipe structure in which an inner pipe is the gas phase cooling medium passage, and a space formed between the inner pipe and an outer pipe surrounding an outer periphery of the inner pipe is the liquid phase cooling medium passage, and wherein the coupling pipe has a shape in which a first end portion of the coupling pipe is inserted into the evaporator section, the coupling pipe extends from the evaporator section toward an outside region of the rotor along the rotational axis, and a second end portion of the coupling pipe is secured to the condenser section, the coupling pipe is configured such that the liquid phase cooling medium flows through the liquid phase cooling medium passage by utilizing a gravitational force, characterized in that the double pipe structure extends over the entirety of the coupling pipe including the bent portion, inside the evaporator section, a first end portion of the gas phase cooling medium passage, which is closer to the evaporator section, protrudes more than a first end portion of the liquid phase cooling medium passage, which is closer to the evaporator section, and an ingress prevention section is provided inside the condenser section and for preventing ingress of the liquid phase cooling medium into the gas phase cooling medium passage.