The invention provides a combine harvester which is reduced in the number of connecting components of an engine body frame and an auxiliary reaping device, and is reduced in the number of maintenance and overhaul operation, and deformation of the engine body frame is prevented. The project is solved through the following scheme. A side of a feeder housing (20), opposite to the side which is configured with an control portion (8), is provided with a first conversion mechanism (28B) which converts rotation in a direction from an engine (E) to reciprocating rotating motion and drives a harvest cutter device (50), and a second conversion mechanism (25B) which converts rotation in a direction from the engine (E) to reciprocating rotating motion and drives an auxiliary reaping device (90).