To easily ensure engine output conformed to the actual state of work by setting the reference value to the middle in correspondence with the quantity of material to be thrashed, setting a plurality of working modes in an area between the large quantity value side and the small quantity value side, and selecting the working mode according to the detected result of the quantity of material to be thrashed.

In a combine equipped with a reaping device and a thrashing device, a plurality of working modes W1-W3 are set to the respective areas of the large quantity value side and the small quantity value side, with the reference value as a middle zone on the basis of the quantity of second treated material detected by a second sensor S. A controller 6 is put in an executing state by the on operation of an automatic switch S1 and computes according to detected information of the second sensor S, a rotation sensor S2, and the like to control actuation of actuators M-M2. An engine 2 drives the governor actuator M according to a control signal of the working mode selected on the basis of the detected information of the second sensor S so as to automatically control and adjust a governor 5.