PURPOSE: To adjust the engine speed accurately and responsively by fixing a governor device main body at a throttle shaft for actuating the switching of the throttle valve in a carburetor and transmitting the rotation of an engine to the rotation axis of the governor device main body through a rotating force transmitting mechanism.

CONSTITUTION: A governor device main body 13 is disposed in the position such that the oscillating shaft 3 of the main body 13 and the throttle shaft of a carburetor 14 are on the coaxial line as well as the oscillating shaft 3 and the throttle shaft 11 are directly connected so that the throttle shaft 11 is rotated directly by the oscillating shaft 3. In addition, a driving side pulley 17 is fixed at the rotation axis 16 in an engine main body 15, a driven side pulley 18 is fixed at the rotation axis 1 of the main body 13, and a belt 19 is mounted across both these pulleys 17, 18 so as to transmit the rotation of the engine to the rotation axis 1 of the main body 13. Accordingly, the rotating force of the oscillating shaft 3 is transmitted directly to the throttle shaft 11 so as to adjust the aperture of a throttle valve with the linear torque characteristic proportioned to the engine speed regardless of the aperture position.