The gelatin sol obtained by heating to dissolve amply, preferably with degassing, is Various methods may be employed for discharging the gelatin sol through a spinneret into a coagulation bath to be formed by spinning into a streamlined shape, that is, a profile shape similar to that of natural processed shark fins as shown in FIG. 3. For example, while the coagulating solution is caused to flow at a constant speed of the order of 50 to 100 m/min. through a trough, the gelatin sol is discharged out into the stream. When the leading end of the fibrous gelatin sol formed contacts the coagulating solution, the fibrous gelatin is torn off by the flowing of the solution at a certain length, and immersed as it is in the solution for 3 to 5 minutes, whereby the gelatin coagulates and is formed in a streamlined shape pointed narrowly at both ends of its profile. The formed product is taken out, washed thoroughly with water and freed of excess water, whereupon a shark fin analog is obtained. After washing with water, a calcium salt or an aluminum salt may be further added for hardening of the gelatin fibers.