To provide a decomposition method of chlorofluorocarbon gas and a decomposition device thereof which makes chlorofluorocarbon gas harmless.

The decomposition device of chlorofluorocarbon gas is provided with: a reaction vessel into which the chlorofluorocarbon gas is supplied; a plurality of carbon fiber pieces which are arranged in the reaction vessel; and a microwave applying means which applies microwave so as to generate microwave discharge between the carbon fiber pieces, wherein the chlorofluorocarbon gas is decomposed by the microwave discharge generated between the carbon fiber pieces by microwave application. Further, decomposition gas generated by the decomposition of the chlorofluorocarbon gas is made harmful by a decomposition gas detoxifying means.