A turbine nozzle that is used in a radial turbine, the turbine nozzle comprising: a ring-shaped hub that has a central axis; a plurality of nozzle vanes that are arranged at equal angular intervals on the hub along a circumferential direction of the hub, the plurality of nozzle vanes including a first nozzle vane and a second nozzle vane which adjoin along the circumferential direction of the hub; and a flow path that is formed between a ventral surface of the first nozzle vane and a back surface of the second nozzle vane, wherein, provided that a direction from an outer peripheral side of the hub toward an inner peripheral side of the hub is defined as a flow direction of working fluid in the flow path, the flow path includes a throat that has a smallest flow path cross-sectional area with respect to the flow direction, the flow path cross-sectional area increases on a downstream side of the throat with respect to the flow direction, wherein an airfoil center line of each of the plurality of nozzle vanes includes a first portion and a second portion, the first portion is a portion that extends from an upstream end of the airfoil center line to a first point, the first point being a point where the airfoil center line starts to curve in a direction toward the central axis, the second portion is a portion that extends from the first point to a downstream end of the airfoil center line, and that average rates of change in an angle β in the first portion are positive values, the second portion includes a second point where the average rates of change in the angle β change from positive values to negative values, and the average rates of change in the angle β in a section from the second point to the downstream end are negative values, wherein the angle β is an angle of gradient of the airfoil center line at an intersection of the airfoil center line with and relative to an axis extending radially inwardly from the intersection to the central axis, characterised in that heights of the first nozzle vane on the downstream side of the throat with respect to the flow direction are greater than heights (h) of the first nozzle vane in the throat and gradually increase from an upstream side toward the downstream side with respect to the flow direction. a ring-shaped hub that has a central axis; a plurality of nozzle vanes that are arranged at equal angular intervals on the hub along a circumferential direction of the hub, the plurality of nozzle vanes including a first nozzle vane and a second nozzle vane which adjoin along the circumferential direction of the hub; and a flow path that is formed between a ventral surface of the first nozzle vane and a back surface of the second nozzle vane, wherein, provided that a direction from an outer peripheral side of the hub toward an inner peripheral side of the hub is defined as a flow direction of working fluid in the flow path, the flow path includes a throat that has a smallest flow path cross-sectional area with respect to the flow direction, the flow path cross-sectional area increases on a downstream side of the throat with respect to the flow direction, wherein an airfoil center line of each of the plurality of nozzle vanes includes a first portion and a second portion, the first portion is a portion that extends from an upstream end of the airfoil center line to a first point, the first point being a point where the airfoil center line starts to curve in a direction toward the central axis, the second portion is a portion that extends from the first point to a downstream end of the airfoil center line, and that average rates of change in an angle β in the first portion are positive values, the second portion includes a second point where the average rates of change in the angle β change from positive values to negative values, and the average rates of change in the angle β in a section from the second point to the downstream end are negative values, wherein the angle β is an angle of gradient of the airfoil center line at an intersection of the airfoil center line with and relative to an axis extending radially inwardly from the intersection to the central axis, characterised in that heights of the first nozzle vane on the downstream side of the throat with respect to the flow direction are greater than heights (h) of the first nozzle vane in the throat and gradually increase from an upstream side toward the downstream side with respect to the flow direction.