To suppress gear shift contrary to the intention of a driver when alerting to the driver by changing the magnitude of the reaction of the accelerator pedal of a vehicle.

This control device for a transmission controls a transmission 10 when alerting to the driver by changing force applied from the accelerator pedal 113 of the vehicle to the driver. When force applied from the accelerator pedal to the driver is changed at the time of alerting, the transmission is controlled to be hardly shifted in comparison with a case that force applied to the driver is unchanged. When force applied to the driver is changed, included are a transient state that force applied to the driver is changed from an unchanged state, a constant state that force applied to the driver is changed, and a state that force applied to the driver at the time of finishing alerting is returned to the unchanged state.