An electric power generation control apparatus mounted to a motor vehicle predicts an operational point of an internal combustion engine in the future based on driving path information supplied from a navigation system mounted to the motor vehicle. The apparatus further predicts an increased amount of fuel consumption which is caused by electric power generation of an alternator based on the predicted operational point of the internal combustion engine. The apparatus sets a reference value of an electric power economy index which is an amount of fuel consumption per electric power generation. On driving the motor vehicle on a path, the apparatus sequentially predicts the operational point of the internal combustion engine, and controls the alternator so that the actual electric power economy index becomes equal to the reference value based on the operational point of the internal combustion engine predicted.