Disclosed is an apparatus including a stepless speed change device receiving an engine drive; a planetary transmission device for, by a plurality of planetary transmission mechanisms, combining an output from the stepless speed change device and the engine drive not subject to a speed change by the stepless speed change device; and a speed range setting device for outputting the drive combined by the planetary transmission device and divided into a plurality of speed ranges. The planetary transmission device, the speed range setting device and a forward-reverse changeover device are located forwardly of a rear end of an upstream transmission case portion. An electric motor may be used instead of the stepless speed change device.