With a view to utilizing fish skin gelatin as a clearifier or chewing gum base, yellowfin sole skin gelatin was succinylated. Up to 10% succinic anhydride to gelatin, the succinylation degree of gelatin was increased linear and above this concentration a nearly constant value was reached. The succinylated gelatin treated with 15% succinic anhydride to gelatin was examined on the reactivity properties with tannic acid in the experiment. Succinylation degree of the gelatin was about 80%. Succinylation shifted the apparent isoelectric point from pH 5.54 in untreated gelatin to pH 4.08 in succinylated gelatin. The proximate composition and amino acid composition of succinylated gelatin were similar to those of untreated gelatin. However lysine composition for succinylated gelatin was lower than for untreated gelatin. The ratio of precipitated gelatin and tannic acid became maximum at pH 4.8 in untreated gelatin, at pH 4.0 in succinylated gelatin. Regardless of the. difference between untreated and succinylated gelatins, the ratio of precipitated gelatin decreased with concentration of gelatin. The ratio of precipitated tannic acid was the highest by adding 2∼4 times in succinylated gelatin to tannic acid weight, by adding 2∼3 times in untreated gelatin. The ratios of precipitated succinylated gelatin and tannic acid were scarcely affected by the presence of sucrose, however, were affected by the presence of ethyl alcohol.