NOVELTY - The cyclic reformer comprises: a plasma reforming reaction unit provided with a mixture of fuel gas and air supplying unit to generate a plasma; a thermal oxidation reaction unit coupled with one end of the plasma reforming reaction unit and for obtaining a primary reformed fuel gas; a unit for reforming the obtained primary reformed fuel gas and connected with other end of the plasma reforming reaction unit to obtain a secondary reformed fuel gas; and a circulation line for conveying the secondary reformed fuel gas. A first housing is formed on the plasma reforming reaction unit.    USE - The cyclic reformer is useful for reforming a fuel gas (claimed) such as hydrogen, carbon monoxide and inert gas including nitrogen and carbon dioxide.    ADVANTAGE - The cyclic reformer has reduced size, so that the reformer is easy to install, and reforms the fuel gas with high yield.    DETAILED DESCRIPTION - The cyclic reformer comprises: a plasma reforming reaction unit provided with a mixture of fuel gas and air supplying unit to generate a plasma; a thermal oxidation reaction unit coupled with one end of the plasma reforming reaction unit and for obtaining a primary reformed fuel gas; a unit for reforming the obtained primary reformed fuel gas and connected with other end of the plasma reforming reaction unit to obtain a secondary reformed fuel gas; and a circulation line for conveying the secondary reformed fuel gas. A first housing is formed on an inner surface of the plasma reforming reaction unit. A second housing is connected with the plasma reforming reaction unit and is provided with an end position of an electrode of the reforming unit. An end of the circulation line is coupled with a regulating unit. A solenoid valve is installed to control the flow of the mixture in the plasma reforming reaction unit. The circulation line is connected with the second housing, and has a sloping shape or a round shape. An inner surface of the reforming unit is mounted on a baffle. A cross-sectional area of the thermal oxidation reaction unit is larger than that of the first and second housings.