Dioxin removal by activated carbon is studied by using a fixed bed type column and 1,2,3,4-tetrachlorinated dibenzo-p-dioxin (T4CDD). Effects of running time, T4CDD concentration of inlet gas, amount of activated carbon used, valid particle diameter of activated carbon, gas temperature, and superficial gas velocity in the column on T4CDD removal were analyzed and cleared. The effects were explained by the model that T4CDD removal is controlled by mass transfer rate in a boundary film on activated carbon particles and in the pores of them. T4CDD removal is little affected by the existence of 1,2,3-trichlorobenzen and sulfur dioxide in the gas phase, and is enhanced by the existence of hydrochloride in the gas phase.