To provide a CO2 decomposition apparatus of a low running cost.

In the carbon dioxide decomposition apparatus, a dispersing plate 2 is formed below a reaction column 1, and a gas containing CO2 is fed from the lower part of the dispersing plate through a gas supply pipe 3. Iron powder is supplied to the reaction part 1b of the reaction column. The iron powder is blown up by the gas to react with the CO2-containing gas in the reaction part 1b so that CO2 is decomposed into C, producing iron oxide. The gas, C, and iron oxide are led to a cyclone 7 where the iron oxide of a large density is separated to fall into a reduction column 8. Hydrogen is supplied from the lower part of the reduction column 8, and the iron oxide is reacted with the hydrogen in the column 8 to be reduced into iron. The hydrogen is produced by a hydrogen production part in which hydrogen is produced from hydrocarbons or reactive particles containing carbon and water vapor by using shock high temperatures generated by shock waves.