Suppresses noise due to high engine speed and improves emission and fuel consumption of a hybrid generator. A difference computing unit 29 computes a first difference between an alternator output and a load output. A difference computing unit 31 computes a second difference between a battery output and the load output. When the battery output is greater than a battery output stopping threshold, the alternator output is fixed and the first difference is compensated for by the battery output. When the battery output is less than the battery output stopping threshold, the engine speed is increased to compensate for the second difference by the output of the alternator 3. To compensate for the second difference, a target engine speed is determined using a relationship of the second difference and the target engine speed. The engine speed is converged at the target engine speed.