A diffuser comprising: a connection section that forms a connection flow passage extending from an outlet of turbine rotor blades and in an axial direction (Da) in which a central axis (C) of a turbine wheel extends so as to guide thereinto through an end thereof on an upstream side an exhaust gas discharged from the turbine rotor blades ; and a body section that forms a body section flow passage extending in the axial direction (Da) in which the central axis (C) of the turbine wheel extends, the body section flow passage having an inlet connected to an end of the connection flow passage on a downstream side so as to guide the exhaust gas that has passed the connection flow passage into the body section flow passage and having a flow passage sectional area on a side of the inlet greater than a flow passage sectional area of the connection flow passage at the downstream side thereof, wherein a shape of a flow passage cross section of the connection flow passage is formed into a circle at the end thereof on the upstream side and into an ellipse or a shape obtained by deforming the ellipse as a basis, at the inlet of the body section flow passage and is formed to be gradually enlarged in a long-axis (A1) direction of the ellipse from the end thereof on the upstream side toward the inlet of the body section flow passage, wherein the connection flow passage has a connection section center axis (C2) as a central axis thereof, wherein the connection section center axis (C2) is formed linearly to overlap the central axis (C) of the turbine wheel , and wherein the connection section center axis (C2) is located at a position deviating from a body section center axis (C3) that is a central axis of the body section flow passage. a connection section that forms a connection flow passage extending from an outlet of turbine rotor blades and in an axial direction (Da) in which a central axis (C) of a turbine wheel extends so as to guide thereinto through an end thereof on an upstream side an exhaust gas discharged from the turbine rotor blades ; and a body section that forms a body section flow passage extending in the axial direction (Da) in which the central axis (C) of the turbine wheel extends, the body section flow passage having an inlet connected to an end of the connection flow passage on a downstream side so as to guide the exhaust gas that has passed the connection flow passage into the body section flow passage and having a flow passage sectional area on a side of the inlet greater than a flow passage sectional area of the connection flow passage at the downstream side thereof, wherein a shape of a flow passage cross section of the connection flow passage is formed into a circle at the end thereof on the upstream side and into an ellipse or a shape obtained by deforming the ellipse as a basis, at the inlet of the body section flow passage and is formed to be gradually enlarged in a long-axis (A1) direction of the ellipse from the end thereof on the upstream side toward the inlet of the body section flow passage, wherein the connection flow passage has a connection section center axis (C2) as a central axis thereof, wherein the connection section center axis (C2) is formed linearly to overlap the central axis (C) of the turbine wheel , and wherein the connection section center axis (C2) is located at a position deviating from a body section center axis (C3) that is a central axis of the body section flow passage. <EOS>