#$%^&*AU2017204570A120170727.pdf#####ABSTRACT To provide a device and a method for oxidation decomposition treatment of a hazardous gas of a volatile organic compound (VOC) or the like at normal temperature. In an embodiment there is 5 provided a gas treatment device comprising: a flow channel through which an ethylene gas to be treated flows； a plasma-generating unit including at least a first electrode, a second electrode, a dielectric material, which are arranged inside the flow channel, and a power-supply unit for supplying AC power at an output frequency 0 of 0.5 kHz or higher and 2.0 kHz or lower, wherein a voltage is applied between the first electrode and the second electrode by the power-supply unit to cause electrical discharging to occur, whereby plasma is generated； and a catalyst medium which is provided in a position where the plasma generated by the 5 plasma-generating unit inside the flow channel is present, is adapted for accelerating a reaction with the gas to be treated, has metallic catalytic particles present on an inorganic substance, and is Pt supported by A1 20 3 . 9238153_1 (GHMatters) P96427.AU.1FIG.1 0 0 (Y) r1Ir 0T O O-
