The tannin acid and the enzymes have been used in order to improve the ruggedness in laundry and the absorption of dyes and pigments in the textile industry for several years. The enzyme processing on the protein fiber minimizes the damage of the entire fiber and improves the dyeability by effectively modifying only the hydrophobic surface. This study tried out the structural observation by applying the Castanea crenata sieb. et. zucc. containing abundant tannin to the hair dyeing as the natural dyeing pigment along with Protease of Rhizopus sp. The dyeability was improved as compared to the dyeing using only the synthetic tanning and iron mordant. When the depth of pigment was higher in accordance with the surface observation, the enzyme dissolution had impact on dyeing and so the keratin layer on the hair surface. Accordingly, it was found that the appropriate depth was between 0.01 and 0.03%. It was estimated that 0.1% protease would treated within 30min. Consequently, it would cause the good reaction with the functional group of tannin pigment.