NOVELTY - A heating gas (22) generated in hot blast generator (19) is circulated to thermal decomposition kiln furnace (1). Indirect heating of waste material (12) is carried out in furnace, and waste is decomposed. The partially decomposed gas (13) is supplied to generator (19), and decomposition is carried out using self-heat. The interior of furnace is adjusted to negative pressure. Pressure balancing of circulated heating gas is adjusted, and interior of hot blast generator is controlled to negative pressure, and thus self-heat decomposition of waste material is enabled.    USE - For self-heat thermal decomposition of waste material, such as municipal solid waste.    ADVANTAGE - The self-heat thermal decomposition of waste material is economically enabled. The requirement of fan at thermal decomposition gas line is eliminated. The obstruction of thermal decomposition gas line is prevented.    DETAILED DESCRIPTION - A heating gas (22) generated in hot blast generator (19) is circulated to thermal decomposition kiln furnace (1) with external heat. Indirect heating of waste material (12) is carried out in furnace, and waste material is thermally decomposed. The partially decomposed gas is supplied to generator (19), and thermal decomposition is carried out using self-heat. The surplus thermal decomposition gas is burned. The interior of furnace is adjusted to negative pressure, by discharging waste material passed through waste gas processing apparatus (A), and sucking. Pressure balancing of circulated heating gas is adjusted, and interior of hot blast generator is controlled to negative pressure. The partially decomposed gas is decomposed with self-heat, and self-heat thermal decomposition of waste material is enabled. An INDEPENDENT CLAIM is included for self-heat thermal decomposition apparatus.    DESCRIPTION OF DRAWING(S) - The figure shows the schematic view of thermal decomposition apparatus.    Thermal decomposition kiln furnace (1)    Waste material (12)    Thermal decomposition gas (13)    Hot blast generator (19)    Heating gas (22)    Waste gas processing apparatus (A)