Abstract: A throttle device comprises a throttle valve having a circular body and a compensation member made of resin. The body has an upstream half rotatable at an upstream side with respect to a throttle shaft and a downstream half rotatable at a downstream side with respect thereto. The compensation member is installed on the upstream half at a downstream side thereof and bulged toward an inner wall of a throttle body. When the throttle valve rotates in an open direction from a closed position, the area of an intake air passage at the upstream half is smaller than the area of a passage at the downstream half and thus, the difference between the flow velocity at the upstream half and that at the downstream half can be reduced. Accordingly, it is possible to restrict the flow of the intake air from becoming oblique to the axis of the intake air passage and hence measure the flow rate of the intake air accurately.