A shift control system includes a belt-type continuously variable transmission (CVT) with primary and secondary pulleys, a shift actuator that regulates an oil pressure supplied to the primary or secondary pulley to vary an actual transmission ratio of the CVT, and a control unit that controls the shift actuator. The control unit sets a target transmission ratio in a first mode when a normal driving range is selected and in a second mode when an engine braking range is selected, drives the shift actuator to adjust the actual transmission ratio to the target transmission ratio, determines a delay time to delay the setting of the target transmission ratio in the second mode at the time of range switchover from the normal driving range to the engine braking range, and holds the target transmission ratio set in the first mode until the delay time has elapsed from the range switchover.