Abstract: A hybrid drive device comprises an internal combustion engine and an energy converter adapted to co-operate with an output shaft of the internal combustion engine and which comprises an electric machine. The electric machine includes a first rotor connected to the output shaft of the internal combustion engine and a second rotor connected to a drive shaft. The two rotors are arranged with surfaces for co-operation by transmitting power through magnetism directed substantially in the direction of the axis of rotation of the rotors for substantially axial magnetic flux between the rotors.