An object is to provide a type of device capable of properly cooling a bearing of a throttle body even under a condition that the throttle body receives heat of high-temperature intake air or exhaust gas. In the present invention, an engine coolant passage that guides a coolant of an engine is provided integrally with a member fixing a bearing to be adjacent to a circumferential wall of the bearing of the member fixing the bearing, which supports a throttle shaft, and heat transferred from the bearing (or likely to be transferred to the bearing) via the member fixing the bearing is carried away to the outside of a throttle body by the engine coolant.