In order to develop a new type of food source for the effective utilization of fish protein, plastein reaction was applied to improve the functional properties of filefish protein. Plasteins were synthesized from a peptic filefish protein hydrolysate by papain, pepsin, $alpha-chymotrypsin$ and protease(from Streptomyces griceus) under the optimum conditions of previous paper). Also, L-glutamic acid diethylester and L-leucine ethylester were incorporated into plastein during the plastein reaction by papain. And, General composition, yield, molecular weight, amino acid composition, color and IR spectrum of plasteins were measured. The protein, ash and lipid content of the plasteins were $72~78\%,;7.4~11.8\%;and;0.3~0.9\%$ respectively. The yield of plasteins were papain $55.0\%,;pepsin;47.6\%,;alpha-chymotrypsin;38.3\%,;protease;23.6\%$, glutamic acid-incorporated plastein (Glu-Plastein) $35.0\%$, and leucine-incorporated plastein (Leu-plastein) $45.7\%$. The glutamic acid and leucine content in Glu-plastein and Leu-plastein were $38.7\%,;41,7\%$, respectively, while the contents in the peptic filefish protein hydrolysate were $16.01\%;and;8.16\%$, respectively. The amino acid compositions were similar to that of the original filefish muscle protein. The major molecular weights of the peptic hydrolysate estimated by gel filteration were 2,000 and 310, and those of plasteihs were 21,000 and 4,900 for papain, 24,000 for pepsin, 18,500 for $alpha-chymotrypsin$ 6,700 for protease, 24,000 for Glu-plastein and 17,000 for Leu-plastein. The structural changes in freeze-dried filefish meat, the FPC and hydrolysate were not observed on the IR spectrum. But plasteins showed amide I band in $1,600~l,700cm^{-1}$ range and resulted in a strong band in $800~850;cm^{-1},;700~750;cm^{-1};and;650~700;cm^{-1}$. The amide I band of Glu-plastein was wider than those of other plasteins and had also a small band at $1,440;cm^{-1}$.