A transmission device for a work vehicle, comprising a travel drive system for transmitting engine power to a travel device; an implement drive system for transmitting engine power to an external power take-off shaft; braking operation tools for a braking operation; a stop operation mechanism provided to the travel drive system and capable of interrupting the transmission of power to the travel device; and a hydraulically operated PTO clutch for interrupting the transmission of power to the external power take-off shaft, the PTO shaft being provided to the implement drive system; wherein the stop operation mechanism and the PTO clutch are linked with the braking operation tools so that the stop operation mechanism is operated to a power transmission stopping position and the PTO clutch is disengaged along with a pressing operation of the braking operation tools, and the PTO clutch is engaged along with a press-releasing operation of the braking operation tools; and an operation timing is set so that the PTO clutch is disengaged after traveling is detected to have stopped when the braking operation tools are operated in the pressing direction, and that the PTO clutch is engaged before traveling is started when the braking operation tools are operated in the press-releasing direction.