A generating device including a magneto generator, wherein: an AC control voltage is applied to an armature coil of the magneto generator from a battery via an inverter to change a phase angle of the AC control voltage, thus increase/reduce an output of the magneto generator and match the output of the generator with a target value; it is determined that a characteristic, in which the output of the magneto generator increases when the phase angle of the AC control voltage is delayed, is a normal control characteristic, and a characteristic, in which the output of the magneto generator decreases when the phase angle of the AC control voltage is delayed, is a reciprocal control characteristic; and it is determined whether a present control characteristic of the output of the generator relative to the phase angle of the AC control voltage is the normal control characteristic or the reciprocal control characteristic to decide, based on a determination result, a changing direction of the phase angle of the AC control voltage when the output of the generator is controlled and brought close to the target value.