A variable-geometry turbocharger comprising: a turbine housing in which a turbine impeller is rotatably provided; a bearing housing in which a rotor shaft connected with the turbine impeller is rotatably provided; a variable nozzle unit capable of altering a passage area of an exhaust gas to be supplied to the turbine impeller; a support ring attached to the variable nozzle unit, including an outer peripheral edge portion pressed by and held between a side surface of the turbine housing and a side surface of the bearing housing; and a seal structure configured to inhibit liquefied unburned fuel from leaking from between the side surface of the turbine housing and the side surface of the bearing housing, the liquefied unburned fuel used for regenerating a filter arranged downstream of an outlet of the turbine impeller in the variable-geometry turbocharger, the seal structure comprising: at least one annular mounting step portion (91, 99) formed in at least one of the side surface of the turbine housing and the side surface of the bearing housing outside the support ring in radial directions of the support ring; and an annular gasket provided in the mounting step portion (91,99), wherein the gasket is pressed by and held between a bottom surface of the mounting step portion in the turbine housing and the side surface of the bearing housing, between a bottom surface of the mounting step portion in the bearing housing and the side surface of the turbine housing, or between the bottom surface of the mounting step portion in the turbine housing and the bottom surface of the mounting step portion in the bearing housing. a turbine housing in which a turbine impeller is rotatably provided; a bearing housing in which a rotor shaft connected with the turbine impeller is rotatably provided; a variable nozzle unit capable of altering a passage area of an exhaust gas to be supplied to the turbine impeller; a support ring attached to the variable nozzle unit, including an outer peripheral edge portion pressed by and held between a side surface of the turbine housing and a side surface of the bearing housing; and a seal structure configured to inhibit liquefied unburned fuel from leaking from between the side surface of the turbine housing and the side surface of the bearing housing, the liquefied unburned fuel used for regenerating a filter arranged downstream of an outlet of the turbine impeller in the variable-geometry turbocharger, the seal structure comprising: at least one annular mounting step portion (91, 99) formed in at least one of the side surface of the turbine housing and the side surface of the bearing housing outside the support ring in radial directions of the support ring; and an annular gasket provided in the mounting step portion (91,99), wherein the gasket is pressed by and held between a bottom surface of the mounting step portion in the turbine housing and the side surface of the bearing housing, between a bottom surface of the mounting step portion in the bearing housing and the side surface of the turbine housing, or between the bottom surface of the mounting step portion in the turbine housing and the bottom surface of the mounting step portion in the bearing housing. at least one annular mounting step portion (91, 99) formed in at least one of the side surface of the turbine housing and the side surface of the bearing housing outside the support ring in radial directions of the support ring; and an annular gasket provided in the mounting step portion (91,99), wherein the gasket is pressed by and held between a bottom surface of the mounting step portion in the turbine housing and the side surface of the bearing housing, between a bottom surface of the mounting step portion in the bearing housing and the side surface of the turbine housing, or between the bottom surface of the mounting step portion in the turbine housing and the bottom surface of the mounting step portion in the bearing housing.