Cultivator

Driving worm (33) provided on a transmission shaft (31), driven worm wheel (34) provided on a cultivating shaft (71), main shaft portion (35) of the transmission shaft (31) and clutch (20) are collectively accommodated in a transmission casing (40), which includes first and second bearings (51, 52)for preventing the clutch and driving gear from being displaced toward each other. The main shaft portion (35) is screw-coupled to the clutch and a direction in which the screw-coupling between the main shaft portion and the clutch is tightened corresponds to only one rotational direction of an engine (11). The casing (40) has a single opening (43) for inserting therein the worm and worm wheel, and the opening is closed with a lid (60) that also functions to prevent the worm from coming off the casing.