NOVELTY - A methane gas decomposition apparatus comprises methane gas supply path which supplies methane gas, circuit connected to methane gas supply path, reaction tube (3) which is provided in circuit and has a pair of discharge electrodes (30a, 30b) where electricity is supplied, carbon isolation part which is provided downstream from reaction tube of circuit and isolates carbon of reactive gas, hydrogen separation part which is provided downstream from carbon isolation part of circuit and isolates hydrogen from reactive gas with which carbon is isolated, and gas supply section.    USE - A methane gas decomposition apparatus (claimed).    ADVANTAGE - Adhesion of pulverized carbon to reaction tube and electrode part is prevented, and methane gas is efficiently and continuously decomposed.    DETAILED DESCRIPTION - A methane gas decomposition apparatus comprises methane gas supply path which supplies methane gas, circuit connected to methane gas supply path, reaction tube (3) which is provided in circuit and has a pair of discharge electrodes (30a, 30b) where electricity is supplied, carbon isolation part which is provided downstream from reaction tube of circuit and isolates carbon of reactive gas, hydrogen separation part which is provided downstream from carbon isolation part of circuit and isolates hydrogen from reactive gas with which carbon is isolated, gas supply section, supply ports (34a, 35a), and exhaust ports (35b) for exhausting. Circuit is provided in downstream of hydrogen separation part and upstream of reaction tube. Methane gas and unconverted gas supplied through methane gas supply path are supplied to reaction tube with specified pressure. Part of gas supplied to reaction tube through gas supply section is supplied so that carbon generated between discharge electrodes may be pulverized. The methane gas decomposition apparatus continuously produces reactive gas containing carbon and hydrogen by decomposing methane gas.    DESCRIPTION OF DRAWING(S) - The drawings show schematic diagrams of discharge electrodes in the reaction tube.    Reaction tube (3)    Discharge electrodes (30a, 30b)    Connecting terminals (32a, 32b)    Supply ports (34a, 35a)    Exhaust ports (35b)