PROBLEM TO BE SOLVED: To provide a combine harvester having an exhaust device which is excessively not heated and is excellent in durability, and a grain tank capable of storing a large quantity of grains.SOLUTION: In the combine harvester, a DPF unit (40) for purifying the exhaust gas of an engine (9) is disposed in a space (S) formed between a thresher (5) and a grain tank (6), a cover (42) is provided for covering at least the upper and lateral sides of the DPF unit (40), and an opening (A) is formed in the lower part of the cover (42).