Abstract: A starting device for an internal combustion engine is described comprising a rotating electric machine the rotor of which is axially translatable with respect to the stator between a rest position and a working position. The rotor is fixed to a transmission shaft bearing a pinion capable of engaging with a corresponding toothed ring of the internal combustion engine when the rotor is in the working position. The starting device is further provided with a controlled-conduction semiconductor device disposed in series with the windings of the stator and the rotor, and an electronic control circuit for the semiconductor device for controlling the intensity of the current supplied to the electric machine.