To decompose environmental pollutants emitted in plasma-utilizing cleaning, near their sources of release.

In an apparatus generating plasma between opposing electrodes P1 and P2, a part or the whole of the wall partitioning the plasma-generating chamber 10K is formed as a transmissive wall 10b capable of transmitting UV rays generated in plasma generation. Titanium oxide 30 is arranged at such a position as to receive the UV rays transmitted through the transmissive wall and lie in the middle of the emission passage for a gas containing the emission gas generated in cleaning an article 20 under the action of plasma.