an input side primary pulley having a groove width which varies according to an oil pressure;

an output side secondary pulley having a groove width which varies according to an oil pressure;

a belt wrapped around the primary pulley and the secondary pulley, a pulley-contacting radius of which varies according to the groove width;

an actuator which varies the oil pressure of the primary pulley according to a driving condition; and

a controller, which

calculates a control deviation of the actuator on the basis of a reference model operating position, which is an operating position of the actuator corresponding to a target speed ratio, an actual operating position of the actuator corresponding to an actual speed ratio between the primary pulley and the secondary pulley, and an operating position deviation amount of the actuator;

determines whether or not to update the operating position deviation amount of the actuator on the basis of a variation in the target speed ratio and the control deviation;

updates the operating position deviation amount of the actuator on the basis of a deviation between the reference model operating position and the actual operating position when the operating position deviation amount of the actuator is determined to update;

controls a line pressure, which serves as a source pressure of the oil pressure of the primary pulley and the oil pressure of the secondary pulley, on the basis of the control deviation;

calculates a primary pulley input torque; and

prohibits the determination of the update for a second predetermined time period when the primary pulley input torque varies beyond a range of a first predetermined value and a second predetermined value, which is smaller than the first predetermined value, during a first predetermined time period.