To solve a problem concerning to waste of clamping force generating energy such as pump driving energy at a gear ratio in which a chain is engaged with movable teeth capable of moving back and forth on the periphery of a pulley center boss section.

Secondary pulley pressure (chain holding pressure) Ps is reduced at ΔPsL only corresponding to the chargeable initial torque value of the movable teeth at an initial time of manufacture from a hydraulic pressure value (slip preventive value with chain holding pressure only) PsL at a normally fixed A1 point. If a slip rate deviation ΔS=|S-So| between a slip rate S of the chain at a reduced state and an initial slip rate So (=0) of the chain at the initial time of manufacture is an allowable upper limit value ΔSmax or below as being shown at an A2 point, a secondary pulley pressure correction amount (chain link holding pressure correction amount) ΔPsH for making the slip rate deviation ΔS set at zero as being shown at an A3 point is calculated, and Ps= PsH=PsL-ΔPs obtained by making the secondary pulley pressure Ps reduce and correct ΔPsH only from the hydraulic pressure value PsL at the A1 point is used for chain holding pressure control of the secondary pulley at the highest gear ratio.