PURPOSE: To reduce a cost and to lower a heating temp. without using highly corrosive materials and without generating drastic materials by reducing the zinc oxide in carbonization char to zinc with a reducing gas and evaporating the zinc.

CONSTITUTION: Waste tires are thermally decomposed to oil-components and the carbonization char in a carbonization furnace 10. The evaporated oil-components are liquefied in a condenser 12 and the liquid is recovered in an oil recovering device 14. The gaseous components which cannot be liquefied in the condenser 13 are introduced to a secondary combustion furnace 16, where the components are burned. The waste gases thereof are treated in a waste gas treating device 18 and are released into the atm. The waste tire carbonization char obtd. by carbonization is pulverized to a prescribed grain size in an iron removing device 20 and after the metallic components are removed therefrom, the pulverized char is washed with water and is dried in a dryer 22. The dried char is charged into a dezincification furnace 24 containing a reducing gaseous atmosphere, where the ZnO remaining in the char is reduced to Zn with the reducing gases, such as CO and H2; thereafter, Zn is evaporated and the dezincification of the char is executed. The carbonization char from which the zinc is removed is subjected to an activation treatment in an activation furnace 26 and is then cooled by a cooler 28, by which the active carbon as the product is obtd.