PURPOSE: Provided is a miniaturized traveling transmission for working machines for transmitting engine power to right and left axles with engine speed changed by a static hydraulic type continuously variable transmission. CONSTITUTION: The working machine includes an engine; a static hydraulic type continuously variable transmission(30) with a pump unit(33) and a motor unit(34); a mission case(10) to receive the power speed changed by the static hydraulic type continuously variable transmission; right and left axles(13a,13b) positioned from right to left of the mission case; and a right and left traveling device operatively connected to each of the right and left axles, an input shaft(11) of the pump unit being operatively connected to an output shaft of the engine while the output shaft(31) of the motor unit being operatively connected to right and left axles is characterized in that the input shaft(11) of the pump unit and the output shaft(31) are installed extending parallel against the right and left axles and also are connected to a port block(32) to install a passage to contact the pump unit and motor unit, and a unit chamber(19) to receive the pump unit and the motor unit is installed inside the mission case.