Throttle device for internal combustion engine

A throttle valve (2) is rotatably disposed in an air passage (15) formed in a throttle body (1). An amount of air supplied to an internal combustion engine is controlled by rotating the throttle valve. The throttle valve (2) connected to a throttle shaft (3) and the throttle body (1) are formed at the same time by injecting molten resin into a molding die, in which a pair of bearing holders (6, 7) and the throttle shaft (3) are set at predetermined positions. After the throttle body (1) is taken out of the molding die, a pair of bearings (4, 5) are press-fitted into the bearing holders (6, 7) so that the throttle shaft (3) is rotatably supported in the throttle body by the bearings (4, 5). In this manner, deformation of the bearings (4, 5) in the molding process is avoided, and smooth rotation of the throttle valve (2) is secured.