A power transmission apparatus for a work vehicle comprises a speed change device for shifting power from an engine and transmitting the power to a propelling line, a forward/reverse drive switching device for switching power from the engine between forward drive and reverse drive, a PTO shaft for taking off working power, a working transmission line for transmitting power from the engine to the PTO shaft, a clutch element for establishing and breaking power transmission from the engine to the PTO shaft, and a transmission case. The transmission case includes a first housing space for housing the speed change device, and a second housing space defined rearward of the first housing space for housing the forward/reverse drive switching device. The clutch element is housed in the first housing space.