PURPOSE: To easily remove mud adhering to a crawler at the necessary time by removably providing a scraper, for removing mud adhering to the inside of a caterpillar belt, on a position approachable to the belt surface of a caterpillar belt and a shunting position.

CONSTITUTION: In a device in which a rubber-made crawler, a caterpillar belt 6, is wound on a front side drive sprocket and a rear side adjusting rotation wheel to be rotated, a scraper 7 is fixedly provided on an arm rod 13 whose base part is axis-mounted on a supporting axis 12, and the supporting axis 12 is made rotatable with a gear 11 rotated by the telescopic operation of a hydraulic device 10. When harvesting work in a wet paddy is made with a combine, the weight of the caterpillar belt 6 is increased with mud adhering to it to make a sure propelling action difficult. Then mud-removing work is made with an under carriage 2 stopped, and in this case, first the hydraulic device 10 is actuated to approach the upper surface of the lower side caterpillar belt 6. Next the caterpillar belt 6 is rotated to scrape the adherent mud off with the scraper 7.