This paper aims to control a traction-drive stepped variable transmission which slides the roller surface during shifting. Its μ-V characteristic varies largely with respect the frictional heat caused by the sliding, and hence the conventional shift control does not always achieve good ride comfort. In the proposed control system, during the inertia phase, the revolution response of the driving motor is controlled with respect to its status change in order to prevent the friction coefficient from changing faster than the time response of the variable speed motor (ACTR), and simultaneously, the pressing force dominating the ride quality is controlled with predicting the time change of the friction coefficient in order to reinforce the tracking performance of ACTR. The experimental result of the practical vehicle demonstrates that the proposed control system allows the traction drive to shift more smoothly and quickly than the gear transmission.