A transmission control system can reduce degradation of engine characteristics upon shifting operation and can reduce a load on the side of a clutch and a transmission due to delay of response. The transmission control system includes an engine generating a driving force, a transmission having a plurality of gear positions for transmitting the driving force developed by the engine to driving wheels, a clutch for connecting said engine and said transmission, engine control means for controlling the engine, transmission control unit for switching gear positions of the transmission, and clutch control unit for controlling disengagement and engagement of the clutch. The transmission control system further includes an electric motor connected to a drive shaft of the engine and capable of performing regenerating operation, and motor control unit for controlling said electric motor for driving the electric motor for generating a driving force or for performing regenerating operation. The motor control unit transmits said driving force to the driving wheel upon shifting operation by the transmission and performs regenerating portion by an energy from the driving wheels.