NOVELTY - A gas-purification apparatus (10) has treatment tank (I), gas supplier (I), and pressure reduction exhausting unit (I). An organic silicon group impurity adsorption agent (12) consisting of a high silica molecular sieve is arranged in tank (I) so that one side of the tank is divided from the other. A sulfur group impurity adsorption agent (13) consisting of a high silica zeolite is arranged in the similar manner.    USE - For purifying original gas, such as biogas, discarded heat crack gas (both claimed), sewage digestion gas, organic-refuse fermentation methane gas, and thermal decomposition gas of waste materials, such as garbage, containing sulfur group and organic silicon group impurities, and using purified gas as fuel in gas engines and micro gas turbines for electric power generation.    ADVANTAGE - The gas-purification apparatus is compact and economical, and provides high-purity gas with improved yield by a simple and efficient method. The pressure loss is reduced, and use of a small blower is enabled.    DETAILED DESCRIPTION - A gas-purification apparatus (10) has treatment tank (I), gas supplier (I), and pressure reduction exhausting unit (I). An organic silicon group impurity adsorption agent (12) consisting of a high silica molecular sieve which adsorbs the organic silicon group impurity (1a), is arranged in tank (I) so that one side of the tank is divided from the other. A sulfur group impurity adsorption agent (13) consisting of a high silica zeolite which adsorbs the sulfur group impurity (1b) is arranged in a similar manner. The gas supplier circulates the original gas (1) containing the impurities from one side of tank (I) to the other side. The exhausting unit evacuates tank (I).    DESCRIPTION OF DRAWING(S) - The figure shows the outline block diagram of the gas-purification apparatus. (Drawing includes non-English language text).    Original gas (1)    Organic silicon group impurity (1a)    Sulfur group impurity (1b)    Purified gas (1d)    Gas-purification apparatus (10)    Organic silicon group impurity adsorption agent (12)    Sulfur group impurity adsorption agent (13)