In an electronically controlled throttle apparatus, a coil spring is shaped to extend from a U-shaped hook portion which is a joint between a first spring portion having a returning function and a second spring portion having an opening function to the other end of the second spring portion. A coating of a lubricant is provided on a sliding contact area between the inside circumferential surface of the coil spring and the outside circumferential surface of the second spring inside circumferential guide. Thus, the sliding resistance in relative motion between the coil spring and the second spring inside circumferential guide can be significantly reduced.