This experiment was executed to clarify the optimum condition of reductive bleaching for 100% color papers. The reductive bleaching of the color paper was desirable to be done under such conditions as high temperature over $60^{circ}C$ and high consistency within possibly short time. The FAS bleaching like the sodium hydrosulfite required oxygen-free condition. Especially, as the mixture between pulps and chemicals was favored in case of the high consistency, it was actively recommended. Therefore, it is desirable to control the dosage with the type of the dyes, the nature, the dye content, the paper compositions, and the targeting initial and final brightness.