To provide a device which optimizes an input two dimensional information of a control map for selecting a change gear ratio, even when an auto-cruise device or a vehicle speed regulation device is provided in an engine control circuit, and performs an appropriate transmission control even when an opening of an acceleration pedal does not coincide with fuel flow rate for the engine.

Information of the fuel flow rate sent out from an engine ECU is utilized instead of the information of the opening of the acceleration for one of the tow dimensional information of the control map for selecting the change gear ratio of the transmission. In concrete term, the signal sent out to the bus of the communication specification J1939 is utilized.