The method and extractor relate to dentistry and are intended for extraction of metal instruments fragments from a root canal of the tooth, as these instruments may be broken and may get stuck here, for example, during endodontic treatment. According to the invention, two insulated metal electrodes assembled as a cylinder are inserted into the root canal until electric contact with the fragment to be extracted. Then electric current impulse is ran through the circuit formed by the first electrode, metal fragment and second electrode; the intensity and duration of the electric impulse shall be sufficient for welding of the fragment to the electrodes by means of heating at the contact points; this time a heating of the surrounding tissues remains at the physiologically acceptable level; afterwards the electrodes are extracted from the root canal together with the fragment. Depending on a clinical situation, electrodes of various size and configuration are used. Electric impulse is generated by the unit comprising a capacitor chargeable by a battery and dischargeable in pulsed mode via controlled electronic switch. The unit also has an indicator of contact resistance between the fragment and the electrodes for a better alignment of their relative positions.