Abstract: The present invention relates to a continuously variable transmission constructed in such a way that it can speed-change the power inputted to an input shaft according to the load applied to an output shaft and transmit the power to the output shaft even though all the gears remain engaged, and in addition reverse operation can also be effectuated in a simple way. Reviewing the construction thereof, it is mainly composed of a speed change system, which receives power generated by an engine, changes speed and transmits it to the output shaft, a speed change controlling system which automatically adjusts the rotational ratio to correspond to the condition of the load on the output shaft, and a reverse rotation system.