PURPOSE: To smoothly and highly efficiently perform ditching work in a field by connecting an evacuatively rotating machine frame to a running machine body, and providing the machine frame with a ditching body, its transmitting mechanism and separating mechanism, and plow member.

CONSTITUTION: An evacuatively rotating machine frame 5 is connected to a running machine body 1 through a connecting mechanism 2, and the machine frame 5 is provided with ditching bodies 14, 15, a transmitting mechanism 30 thereof, and a plow member 20. The machine frame 5 is traveled while sticking the lower parts of the ditching bodies 14, 15 and the lower part of the plow member 20 into a filed (a) by the running machine body 1, and the ditching bodies 14, 15 are rotated by the transmitting mechanism 30 to ditch the field (a) surface. Then, the soil between ditches is scraped by the plow member 20, and the scraped earth (T) is discharged to the sides to form a channel W. At the time of non-working, the machine frame 5 is evacuatively rotated, and in accordance with this, the transmitting mechanism 30 of the ditching bodies 14, 15 is separated from the ditching bodies 14, 15 by a separating mechanism 37.