A transmission control apparatus is used with a vehicle having an internal combustion engine, a transmission connected to the engine and having a plurality of gear positions, and a generator which is disposed between the transmission and drive wheels and which is capable of generating electric power through regenerative braking during deceleration of the vehicle. The control apparatus operates to detect a revolution speed of the internal combustion engine, and to place the transmission in a highest gear position selected from one or more gear positions that enable the engine revolution speed to be maintained at a level not lower than a predetermined lower limit above which the engine can operate by itself (i.e., re-start), when the generator generates electric power through regenerative braking.