PURPOSE: To reduce capacity of a pump by integrally forming an input shaft for front wheels over its whole length, which input shaft transmits power from a gear shifter to a front wheel transmission device, supporting its both ends only by means of bearings, and thereby reducing fluid resistance of lubricating oil in respect to the input shaft for front wheels which may be caused by the bearing parts.

CONSTITUTION: A front wheel transmission gear 1, a static hydraulic stepless transmission 2, a gear shifting device 3 and a rear wheel operation device 5 are arranged in a mission case 4 of a transmission device for front/rear wheels and a PTO shaft of a farm tractor. A pump 2a of the stepless transmission device 2 is interlocked with an input shaft 9 which is interlocked with an engine. An input shaft 11 of the gear shifting device 3 is interlocked with an output shaft 10 from a motor 2b of the stepless transmission device 2. An output shaft 12 of the gear shifting device 3 is interlocked with an input shaft 13 for front wheels. The input shaft 13 for front wheels is integrally formed over its whole length, while its both ends only are held by bearings 25. It is thus possible to reduce fluid resistance of lubricating oil to the input shaft 13 for front wheels which may be caused by the bearing part, and adopt an inexpensive pump.