TRANSMISSION MODE CONTROL SYSTEM

A transmission mode control system includes a control device that controls a transmission mode of a vehicle and a first input device that accepts a switching operation of switching from an automatic transmission mode to a manual transmission mode. The control device includes a processor and a memory. The processor executes a process including: switching the transmission mode from the manual transmission mode to the automatic transmission mode when a switching time elapses after an operation of the first input device by a driver of the vehicle; and extending the switching time by a set time when the driver performs, within a post-switching determination time after the switching time elapses, a certain operation that causes a gear ratio to change in the same direction as a change of gear ratio when the gear shift is executed in response to the operation by the driver before the switching time elapses.