PURPOSE: To secure stability under runaway of an actuator, and minutely adjust an intake air amount under an idling operation with a compact structure.

CONSTITUTION: An acceleration plate 12 is oscillatable according to an operating amount of an acceleration pedal. A motor output plate 11 which is driven by means of a driving motor 7 has a long hole formed eccentrically to a rotational axis. One end of a second connection member connected to a throttle valve 4 is provided with a first abutting pin 10b to be inserted into a long hole of the motor output plate 11 and a second abutting pin 10c abuttable against the acceleration plate 12. When the driving motor 7 is under runaway, a position of the second abutting pin 10c is regulated by means of the acceleration plate 12, and the throttle opening is controllable. When the motor is under an idling condition, a position of the first abutting pin 10b is set, and an intake air amount can be minutely adjusted.