The present invention relates to an industrial high-temperature modification apparatus and a modification method in which a modification furnace is maintained at a temperature of 1000°C or more by combusting coke and at least the upper half of the modification furnace is maintained at a temperature of 1200°C or more by combusting a synthesis gas, so as to modify all carbide supplied to the modification furnace to produce a synthesis gas of 500 m3 or more per hour. The industrial high-temperature modification apparatus according to the present invention comprises: a modification furnace (10) for modifying carbide; a carbide supply port (20) for supplying the carbide to the modification furnace (10); a coke supply part (30) for supplying coke to the modification furnace (10); a first oxygen supply port (40) for supplying oxygen to the modification furnace (10); a water vapor supply port (50) for supplying water vapor to the modification furnace (10); a synthesis gas discharge port (60) formed on the upper por
