This work deals with a novel method of magnetizing inductance investigation using dynamic simulation of self-excited induction generator. As presented in many papers the magnetizing inductance is the main factor of voltage build-up and stabilization of generated voltage for unloaded and loaded conditions. Thus, an accurate model of the dependency of the magnetizing inductance on magnetizing current is crucial for a realistic representation of the voltage build-up. The proposed method is based on a comparison between the data gained from no-load test (only voltage and current measured at stator terminals are needed) and adequate data calculated in the dynamic simulation. The magnetizing inductance curve of a 4.4 kW wound rotor induction machine was investigated by means of the proposed method and the comparison with the measurement is shown and discussed in the conclusion of this paper.