PURPOSE: To prevent nonuniform rotation in an universal transmission shaft, by providing a connecting shaft part in a tractor and intermediate transmission shaft for relaying an output from a PTO shaft to the universal transmission shaft in a specific state.

CONSTITUTION: A connecting shaft part 8 is positioned in the pulling direction behind rear wheels 9 of a tractor 1 and connected to a pulled rod 4. An universal transmission shaft 11 is provided so as to always position the connecting shaft part 8 at the center thereof by an intermediate transmission shaft 12. The connecting shaft part turns the pulled rod behind the rear wheels to prevent the contact and mutually equalize rotation angle at both ends of the universal transmission shaft. Thereby nonuniform motion is prevented.