The present disclosure relates to a microwave reforming apparatus for gas reforming, and provides a new technology of converting carbon dioxide which is a main greenhouse gas generated during combustion, pyrolysis/gasification, and operation of fossil fuels, methane, and dispersions thereof into high-quality fuels. A microwave reforming apparatus according to the present disclosure uses a carbon receptor and thus can solve the conventional problem of price of catalyst and also enables compactification of a device, rapid startup and response time in several seconds, and application of various kinds of product gases including polymer hydrocarbon. Also, the microwave reforming apparatus according to the present disclosure uses its own internal reaction heat at the time of reforming and thus can maintain the optimum operating conditions for a wide range of flow rate and gas properties. Therefore, it is possible to solve the conventional problem with the time required for normal operation and the efficiency of a reforming apparatus.