The apparatus comprises an outermost, an intermediate, and an innermost compartment, the outermost compartment being provided with burners, activated carbon being supplied into, treated in, and removed from the intermediate compartment, and there being communication for gas between the three compartments. In revivification by the direct heating process, reactor gas is supplied into the outermost compartment, heated by the burners, passed into the intermediate compartment to contact the activated carbon being treated, and is then passed into the innermost compartment and exhausted therefrom. In revivification by the indirect heating process, reactor gas is supplied into the innermost compartment, passed into the intermediate compartment for treatment of activated carbon, and then passed into the outermost compartment and is exhausted therefrom, the innermost and intermediate compartments and elements therein being indirectly heated by the burners of the outermost compartment.