Disclosed is an electronic controller which calculates the variable amounts of the thrust in a primary pulley based on the thrusts of the pulleys, the lower limit thrust and the upper limit thrust in the steps of a target change gear ratio limit routine. The electronic controller calculates the limit transmission speeds based on the variable amounts in the steps, and calculates the guard values for limiting the target change gear ratio based on the limit transmission speeds in the steps. An electronic controller limits the target change gear ratio by the guard values thus calculated, and controls the thrusts of the pulleys by feedback control based on the size of discrepancy of the limited target change gear ratio and the current change gear ratio γ.