A centrifugal rotary machine comprising: a rotor rotating about an axis thereof; a casing covering the rotor and forms a flow path; a plurality of impellers that are provided on the rotor, that are arranged in an axial direction and that are configured to feed a fluid suctioned from one side in the axial direction to the outside in the radial direction of the axis by rotating about the axis; and flow paths, each of which is provided between the impellers adjacent to each other in the axial direction, and configured to guide the fluid discharged from an upstream impeller to a downstream impeller, wherein each flow path includes: a diffuser flow path extending from the inside to the outside in the radial direction of the axis and configured to guide the fluid discharged from the upstream impeller to the outside in the radial direction; a return bend portion, one end of which is communicated with the diffuser flow path, and which is a curved flow path configured to guide the fluid guided by the diffuser flow path toward the inside in the radial direction; a guide flow path communicated with the other end of the return bend portion and configured to guide the fluid guided by the return bend portion to the inside in the radial direction and to introduce the fluid to the impeller on the other side in the axial direction; and a plurality of return vanes (250, 251, 252, 253) extending across the return bend portion and the guide flow path in the flow path and disposed at intervals in a circumferential direction of the axis, and wherein a radial position of leading edge (251F, 252F, 253F) of the return vane (251, 252, 253) in each flow path gradually changes in the radial direction along the axial direction with respect to a position of a top portion of an inner wall surface of each return bend portion, and characterized in that the radial position of the leading edge (252F, 253F) of the return vane (252, 253) at a further downstream side is closer to a radial position of the top portion of the inner wall surface. a rotor rotating about an axis thereof; a casing covering the rotor and forms a flow path; a plurality of impellers that are provided on the rotor, that are arranged in an axial direction and that are configured to feed a fluid suctioned from one side in the axial direction to the outside in the radial direction of the axis by rotating about the axis; and flow paths, each of which is provided between the impellers adjacent to each other in the axial direction, and configured to guide the fluid discharged from an upstream impeller to a downstream impeller, wherein each flow path includes: a diffuser flow path extending from the inside to the outside in the radial direction of the axis and configured to guide the fluid discharged from the upstream impeller to the outside in the radial direction; a return bend portion, one end of which is communicated with the diffuser flow path, and which is a curved flow path configured to guide the fluid guided by the diffuser flow path toward the inside in the radial direction; a guide flow path communicated with the other end of the return bend portion and configured to guide the fluid guided by the return bend portion to the inside in the radial direction and to introduce the fluid to the impeller on the other side in the axial direction; and a plurality of return vanes (250, 251, 252, 253) extending across the return bend portion and the guide flow path in the flow path and disposed at intervals in a circumferential direction of the axis, and wherein a radial position of leading edge (251F, 252F, 253F) of the return vane (251, 252, 253) in each flow path gradually changes in the radial direction along the axial direction with respect to a position of a top portion of an inner wall surface of each return bend portion, and characterized in that the radial position of the leading edge (252F, 253F) of the return vane (252, 253) at a further downstream side is closer to a radial position of the top portion of the inner wall surface. a diffuser flow path extending from the inside to the outside in the radial direction of the axis and configured to guide the fluid discharged from the upstream impeller to the outside in the radial direction; a return bend portion, one end of which is communicated with the diffuser flow path, and which is a curved flow path configured to guide the fluid guided by the diffuser flow path toward the inside in the radial direction; a guide flow path communicated with the other end of the return bend portion and configured to guide the fluid guided by the return bend portion to the inside in the radial direction and to introduce the fluid to the impeller on the other side in the axial direction; and a plurality of return vanes (250, 251, 252, 253) extending across the return bend portion and the guide flow path in the flow path and disposed at intervals in a circumferential direction of the axis, and wherein a radial position of leading edge (251F, 252F, 253F) of the return vane (251, 252, 253) in each flow path gradually changes in the radial direction along the axial direction with respect to a position of a top portion of an inner wall surface of each return bend portion, and characterized in that the radial position of the leading edge (252F, 253F) of the return vane (252, 253) at a further downstream side is closer to a radial position of the top portion of the inner wall surface.