A transmission device for work vehicles comprising: an input shaft configured to transmit power from a drive source; a continuously-variable transmission that is disposed on the input shaft and that is configured to transmit power from the input shaft, whereby it is configured to steplessly convert the speed thereof; a reversing clutch device configured to transmit, either in a forward rotational direction or a reverse rotational direction, power outputted from the continuously-variable transmission; a combining clutch device configured to transmit power outputted from the continuously-variable transmission; and a planetary gear mechanism configured to combine power from the drive source and power outputted from the combining clutch device into combined power, wherein the reversing clutch device and the combining clutch device are configured to be switched selectively, whereby the gear ratio is steplessly changed by the continuously-variable transmission so as to perform speed change operation, characterized in that the input shaft, the continuously-variable transmission and the reversing clutch device are disposed upstream of a differential gear mechanism, which distributes power to a right wheel and a left wheel, on the power transmission course; wherein the planetary gear mechanism is disposed between the input shaft and the differential gear mechanism; a first transmission part of the planetary gear mechanism is interlocked with the input shaft; a second transmission part of the planetary gear mechanism is interlocked with the continuously-variable transmission; a third transmission part of the planetary gear mechanism is interlocked with the input unit of the differential gear mechanism; wherein, on the basis of axial direction of the input shaft, the reversing clutch device and the combining clutch device are disposed between the planetary gear mechanism and the continuously-variable transmission; wherein the continuously-variable transmission is disposed near a rear side of a transmission case. an input shaft configured to transmit power from a drive source; a continuously-variable transmission that is disposed on the input shaft and that is configured to transmit power from the input shaft, whereby it is configured to steplessly convert the speed thereof; a reversing clutch device configured to transmit, either in a forward rotational direction or a reverse rotational direction, power outputted from the continuously-variable transmission; a combining clutch device configured to transmit power outputted from the continuously-variable transmission; and a planetary gear mechanism configured to combine power from the drive source and power outputted from the combining clutch device into combined power, wherein the reversing clutch device and the combining clutch device are configured to be switched selectively, whereby the gear ratio is steplessly changed by the continuously-variable transmission so as to perform speed change operation, characterized in that the input shaft, the continuously-variable transmission and the reversing clutch device are disposed upstream of a differential gear mechanism, which distributes power to a right wheel and a left wheel, on the power transmission course; wherein the planetary gear mechanism is disposed between the input shaft and the differential gear mechanism; a first transmission part of the planetary gear mechanism is interlocked with the input shaft; a second transmission part of the planetary gear mechanism is interlocked with the continuously-variable transmission; a third transmission part of the planetary gear mechanism is interlocked with the input unit of the differential gear mechanism; wherein, on the basis of axial direction of the input shaft, the reversing clutch device and the combining clutch device are disposed between the planetary gear mechanism and the continuously-variable transmission; wherein the continuously-variable transmission is disposed near a rear side of a transmission case.