To provide a small-sized mobile agricultural machine which is easily disassembled/assembled for each functional block, mounted on a carrying vehicle or the like to facilitate the carriage of a machine body, miniaturized overall to freely change an accommodation mode, accommodated even in a narrow space, and capable of improving a carrying property and an accommodating property.

Power from an engine 4 is transmitted to a transmission case 3 via a belt transmission 5, and a plowing shaft 11 disposed at the lower portion of the transmission case 3 is driven by the power. The belt transmission 5 comprises a drive pulley 7 fitted to an output shaft 4a of the engine 4, a driven pulley 8 fitted to an input shaft 3a of the transmission case 3, and a transmission belt 9a stretched between the drive pulley 7 and the driven pulley. These components are fitted in the transmission case in advance, and the transmission case 6 is attachably/detachably fitted to the engine 4 and the transmission case 3.