PURPOSE: The drier, the roaster, the reactivator and the supersteam heater, all of which have the same horizontal cross section and electrodes whose numbers decrease successively are piled up in order from the upper side and electricity is fed through a thyrister to obtain high-quality reactivated active carbon with less fluctuation in quality.

CONSTITUTION: The active carbon to be reactivated are made to move down intermittently every time the reactivated carbon is excluded, and passed through ovens with a rectangular cross section by its gravity, while electricity is directly applied to the carbon to be reactivated to generate heat up to high temperature. In this process, the drier 1, the roaster 2, the reactivator 3 and the supersteam heater for reactivation 4 are piled up in order from the top down, further the drier 1 is equipped with four plate electrodes 4 arranged in parallel with an equal distance and a three-phase alternate current adjusted in its voltage is applied through the thyrister 6. The roaster 2 is equipped with three plate electrodes 5 arranged in parallel with an equal distance and two series of single phase alternate currents obtained by means of Scott connection 7 is applied through thyrister 6. The reactivator 3 and the steam heater 4 are equipped with a pair of heaters 5 and a single phase alternate current obtained by means of another Scott connection 7 and a pair of phase-shifting transformers 8 is applied through thyrister 6 to them.