A discharge gas containing PFC gas including CF4 and NF3 generated from a manufacturing process (10) is concentrated at a concentrator (18) and then chromatographically separated at a chromatographic separator (20) with nitrogen as a carrier gas. In this manner, CF4 and NF3 within the PFC gas can be separated. In particular, because the gas is once concentrated at the concentrator (18), chromatographic separation can be efficiently achieved. By independently concentrating CF4 and NF3 obtained by the chromatographic separation, high purity gas constituents of the PFC gas can be obtained, and reused at the manufacturing process (10).