To drastically decrease effective moment arm of the force transmitted between a flexible cable and a throttle valve actuator at the first rotating angel range, to substantially stabilize at second rotating angle range.

A throttle valve actuator 10 for the internal combustion engine comprises at least one opening 14, and a choke valve body 12 admitting air into the combustion chamber communicating to the opening. On a shaft 18 at least one valve 16 is mounted so as to rotate in the opening of the choke valve body. A crank arm 20 is connected to the shaft. A flexible cable is connected to the crank arm at the fixing position 24 adjacent to one end of the flexible cable. A cam 34 for correcting the moment arm of the force transmitted between the flexible cable and the crank arm is connected to the crank arm, the moment arm drastically decreases in first rotating angle range from first namely closing position, and substantially stabilizes in second rotating angle range from second namely opening position.