TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The photocatalyst members are formed in a prescribed shape. The photocatalyst is included in the photocatalyst member or is supported by the catalyst. The catalyst includes at least one element (E2) (less than or equal to 5 wt.%) which are supported by a prescribed catalyst support whose specific surface area is greater than or equal to 10 m2/g. The photocatalyst comprises titanium oxide that reacts under ultraviolet radiation or visible radiation. The adsorbent porous substance has a specific surface area of 10 - 750 (preferably greater than or equal to 200) m2/g and is made by at last one element selected from silica alumina, zeolite, silica gel, zirconia or titania (preferably HY zeolite, HX zeolite, H mordenite, silica alumina or metal silicate). The non-equilibrium plasma is caused by any one of pulse-streamer discharge, silent discharge or surface discharge.Preferred Component: (E2) Is selected from silver (Ag), gold (Au), cerium (Ce), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), lithium (Li), nickel (Ni), manganese (Mn), molybdenum (Mo), led (Pd), platinum (Pt), rhodium (Rh), vanadium (V), tungsten (W) or zinc (Zn). The solid member is made by at least one element selected from among adsorbent porous substance, dielectric substance, clayey substance or synthetic resin.    TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Electrode: The ground electrode has a cylindrical shape whose internal circumferential wall is covered with the insulator, and where the surface electrodes are constituted by spiral coils on an internal circumferential wall of the insulator in a coaxial manner with the ground electrode. The ground electrode is encompassed by the insulator, so that a pair of the surface electrodes are opposite to each other to tightly hold the insulator. The surface discharge electrode further comprises several through holes are formed to penetrate through in a thickness direction, allowing a treated gas to pass.Preferred Apparatus: (A1) Comprises a pair of surface electrodes opposite to each other so as to tightly hold the insulator. The several surface discharge electrodes are in parallel with each other with a prescribed space. The several (M1) are in the space between the surface discharge electrodes adjacent to each other.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The photocatalyst members are formed in a prescribed shape. The photocatalyst is included in the photocatalyst member or is supported by the catalyst. The catalyst includes at least one element (E2) (less than or equal to 5 wt.%) which are supported by a prescribed catalyst support whose specific surface area is greater than or equal to 10 m2/g. The photocatalyst comprises titanium oxide that reacts under ultraviolet radiation or visible radiation. The adsorbent porous substance has a specific surface area of 10 - 750 (preferably greater than or equal to 200) m2/g and is made by at last one element selected from silica alumina, zeolite, silica gel, zirconia or titania (preferably HY zeolite, HX zeolite, H mordenite, silica alumina or metal silicate). The non-equilibrium plasma is caused by any one of pulse-streamer discharge, silent discharge or surface discharge.Preferred Component: (E2) Is selected from silver (Ag), gold (Au), cerium (Ce), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), lithium (Li), nickel (Ni), manganese (Mn), molybdenum (Mo), led (Pd), platinum (Pt), rhodium (Rh), vanadium (V), tungsten (W) or zinc (Zn). The solid member is made by at least one element selected from among adsorbent porous substance, dielectric substance, clayey substance or synthetic resin.