A throttle valve and the throttle body are formed substantially simultaneously in the same dies. When a movable die moves away from a fixed die, a body ejector pin, a valve ejector pin, and a motor housing ejector pin simultaneously push a bore wall of the throttle body, a motor housing, and peripheral edge of the throttle the valve in a radial direction respectively. A deformation of the throttle valve can be avoided because a stress concentration on the metal shaft of the throttle valve is reduced in opening the dies.