PURPOSE: To suppress the occurrence of displacement in a position of a coupling member even when the clearance of a bearing part is increased by a method wherein a coupling member on the throttle position sensor side is formed in an arcuate shape of a plate, a circular member is pressed in a hole formed in the direction of the diameter of a valve stem in a coupling member on the throttle valve stem side, and the two coupling members are brought into contact with each other.

CONSTITUTION: A bearing member 17 pivotally supporting a throttle valve shaft 16 is worn owing to use for a long time and a clearance set at an initial stage is increased. In this case, when idling is applied, the negative pressure of an engine is exerted on a throttle valve body 18 and displacement in a position occurs by a clearance amount. A throttle position sensor 1 is rotated in synchronism with the rotary shaft of a sensor. In this case, a member 11 in a circular shape is pressed in a hole formed in the direction of diameter in the end of a throttle valve shaft 16, and the outer diameter part of the circular member 11 is brought into contact with a protrusion member 12 on the sensor side for coupling. Since the part, making contact with the circular member 11, of a protrusion member 12 on the sensor side is formed in an arcuate shape, even when a position making contact is displaced, a rotation amount of the throttle valve stem 16 is kept at a constantly specified value.