A stepless transmission in which travel in two different shift regions is made possible by a main transmission unit constituting a stepless transmission mechanism and an auxiliary transmission unit coupled to the stepless transmission mechanism, and in which torque ratio is capable of being varied steplessly in response to signals indicative of detected vehicle traveling conditions. The transmission is equipped with a function which improves the feeling of a speed reduction, makes possible a smooth start and provides excellent accelerability, a function which assures that the vehicle will start moving forward reliably, a function which enhances brake durability, and a function enhances safety in the event of motor malfunction.