PURPOSE: To provide the treatment of waste gas from coal fired boilers where mechanical wear of active carbon is decreased to lessen the use quantity of the active carbon and which is extremely economically effective and restrains the concentration phenomenon of C1.

CONSTITUTION: In the two-stage treatment of active carbon dry desulfurization/ denitrification for waste gas from a coal fired boiler, active carbon from a regenerator 4 is supplied to each of a desulftrizer 2 and denitrifier 3 and simultaneously the spent active carbon from the destulfurizer 2 and the denitrifier 3 are individually led to the regenerator 4.