PURPOSE: To obtain the useful substance from shark fin, in a short time, by heating the shark fin to an extent to effect the gelatinization of the surface skin of the fin and the part near the fin protein, and decomposing the gelatinized part by decomposition enzymes.

CONSTITUTION: Shark fin is optionally pretreated, and treated with an acid and then neutralized. The treated fin is heated to gelatinize only the surface skin of the fin and the connective tissue near the fin protein, and then the gelatinized parts are decomposed and removed by the use of a gelatin decomposition enzyme. The treatment of shark fin can be carried out in a short time without emitting fishy smell.