Continuously variable transmission and control method therefore

A continuously variable transmission mounted in a vehicle to shift and transmit output rotation of a driving source, comprising:

• a variator which changes a speed ratio continuously;
• a stepped sub-transmission mechanism provided in series with the variator;
• and
• a transmission control unit which selects either one of an auto mode in which a final through speed ratio as a target value of an overall speed ratio of the variator and the sub-transmission mechanism is set based on a driving condition of the vehicle and the variator and the sub-transmission mechanism are controlled to realize the final through speed ratio or a manual mode in which a gear position of the continuously variable transmission is selected based on an input operation from a driver, the final through speed ratio is set based on the selected gear position and the variator and the sub-transmission mechanism are controlled to realize the final through speed ratio;
• wherein the transmission control unit reduces a hydraulic pressure of a release-side frictional engagement element which is to be released of the sub-transmission mechanism and reduces this reduction amount as an input torque to the sub-transmission mechanism increases at the time of starting a shift when the manual mode is selected, the input torque is positive and the sub-transmission mechanism is to be shifted down.