The physical properties of trout skin gelatin were compared with those of bovine skin gelatin to develop a novel use of fish gelatin. Gelling temperature, melting temperature and jelly strength of trout gelatin were 16.5°C, 16.2°C and 340g, respectively, which were lower than those of bovine gelatin, while springiness of trout gelatin gel tended to be higher than that of bovine gelatin gel. After the freezing-process, bovine gelatin gel became very fragile, while trout gelatin gel showed little change in jelly strength or springiness. The addition of trout gelatin to soybean curd (“tofu” in Japanese) effectively prevented syneresis by freezing and thawing. These results suggest that trout gelatin could be used as a natural additive with syneresis - preventing ability and springiness.