When a through speed ratio, which is an overall speed ratio of a variator and a subtransmission mechanism, varies from a larger speed ratio than a mode switch speed ratio to a smaller speed ratio than the mode switch speed ratio, a gear position of the subtransmission mechanism is changed from a first gear position to a second gear position and the speed ratio of the variator is modified to a large speed ratio side. The mode switch speed ratio is set midway between a low speed mode Highest speed ratio and a high speed mode Lowest speed ratio.