A throttle valve device includes a body, a valve, a valve gear, a motor, an intermediate gear, an intermediate shaft and a cover. A guiding hole is formed in the cover and the intermediate shaft engages the guiding hole. A positioning reference pin is formed in one of the cover and the body at a position around the motor. A positioning reference hole is formed in the other of the cover and the body at a position around the motor. The body and the cover are positioned with respect to each other by both engaging between the intermediate shaft and the guiding hole and engaging between the positioning reference pin and the positioning reference hole. The body and the cover are fixed to each other by a fixing member.