To provide a method and a device for treating exhaust gas, in which dioxins are surely removed from exhaust gas containing dioxins of high concentration and also post-treatment after removal is made easy.

Alkali chemicals sent from an alkali chemicals feeder 40 are added to exhaust gas and acidic gas starting with hydrogen chloride is solidified and removed by a dust collector 10. Thereafter, a powdery carbonaceous adsorbent is introduced from a carbonaceous adsorbent feeder 23 and granular dioxins contained in exhaust gas are adsorbed. Both the powdery carbonaceous adsorbent and gaseous dioxins are adsorbed or stuck to the granular carbonaceous adsorbent filled in a moving bed type adsorption reactor 20 and removed. The carbonaceous adsorbent of the adsorption reactor 20 is regenerated in a desorption regenerator 21 and thereafter sorted by particle diameter in a separator 22 and respectively returned to the adsorption reactor 20 and the carbonaceous adsorbent feeder 23.