To detoxify the waste gas containing fluorocarbons with high decomposition efficiency and at a low running cost while ensuring safety.

In the decomposition method of the fluorocarbons for detoxifying the fluorocarbons, the waste gas containing the fluorocarbons is passed through discharge plasma, then brought into contact with a fluorocarbon decomposition catalyst. Moreover, oxygen and/or hydrogen are mixed to the waste gas containing the fluorocarbons at one or more places among an inlet of a discharge plasma reactor, inside of the discharge plasma reactor, an inlet of a catalyst reactor and inside of the catalyst reactor.