A gear change control system includes: a shift operation member configured to receive a shift range operation; a clutch configured to transmit a torque of an input shaft to an output shaft; a clutch actuator configured to control engagement of the clutch by using a working fluid; a manual valve configured to switch a supply destination of the working fluid to the clutch actuator in accordance with a decided shift range; a shift actuator configured to move the manual valve on the basis of a shift range changing operation of the shift operation member; and an oil pressure control actuator configured to reduce an oil pressure of the working fluid to a target oil pressure after the shift range changing operation received by the shift operation member is started and before the shift actuator moves the manual valve toward a shift range changing destination.