Usually, the speed change control of the transmission is carried out in accordance with a real speed ratio “i” provided based on a primary pulley rotation speed “N1” and a secondary pulley rotation speed “N2”. While, when, at the time of stopping the vehicle, the real speed ratio fails to return to a value corresponding to the lowest speed position of the transmission, it is judged that there is a speed change failure. Upon this judgment, hydraulic pressures “p1” and “p2” for varying practical diameters of the primary and secondary pulleys are fixed to predetermined values “p1(old)” and “p2(old)” provided for such speed change failure.