Abstract: A throttle device is arranged in the midstream of an individual passage consisting of a low-speed individual intake passage and a high-speed individual intake passage on the downstream of a surge tank. A valve body is rotatably provided in the throttle valve device. The inside of the valve body is formed with an in-valve low-speed passage and an in-valve high-speed passage that are adjacently placed with respect to the rotational axis of the valve body. The intake air supply is performed through only the low-speed individual passage when the opening of the valve body is equal to or less than a predetermined value, and through both the low-speed individual intake passage and high-speed individual intake passage when the opening of the body is larger than the predetermined value.