Defluidization and a decline in fluidization quality were observed in reactions involving a decrease in gas volume. This was due to a reduction in gas velocity in the emulsion phase owing to the reactions. The decrease in the gas velocity led to a reduction in the emulsion phase voidage. Finally, a part of the fluidized bed was defluidized and lifted up through the column like a moving piston. In the present study, methanation of carbon dioxide was carried out as a model reaction, and the effect of the two-stage distribution of the fluidizing gas on the improvement of the fluidization quality was investigated. The bed was fluidized by supplying hydrogen from the bottom of the fluidized bed. The other reactant, carbon dioxide, was supplied from the bottom distributor and a secondary gas inlet. By using this method, it was possible to avoid defluidization. The influences of the level of the secondary inlet and the distribution ratio of carbon dioxide on fluidization quality were studied by plotting two parameters that affect fluidization quality.