PURPOSE: To enable safe travel with an engine prevented from overloading even in travel at the time other than reaping operation.

CONSTITUTION: In a combine equipped with a car speed controller (controlling circuit) (29) for carrying out car speed control based on an increase or a decrease in load on an engine (16), a controlling means, having a grain culm sensor (34) for sensing grain culms fed to a threshing part (4) and automatically controlling the increase and decrease in car speed when sensing the grain culms with the grain culm sensor (34) and a car speed controlling means capable of only automatically reducing and controlling the car speed at the time of sensing no grain culm are installed in the car speed controller (29).