Manufacturing method for a throttle body of an internal combustion engine and a related throttle apparatus

A throttle apparatus comprises a resinous throttle body (211) having an intake passage (211a) therein, a valve member (213) rotatably provided in the intake passage (211a) to adjust an intake air flowing in the intake passage (211a), and a throttle shaft (212) rotating together with the valve member (213), wherein at least one axial end of the throttle shaft (212) is directly supported by the throttle body (211).