This chapter introduces the development of enzymatic hydrolysate of fish elastin and also discusses its underlying mechanism. The skipjack bulbus arteriosus has been used for the production of elastin hydrolysate, due to the availability and abundance of resource. The chapter explains the impact of ingestion of the elastin hydrolysate in the skin and blood vessels. To explore the mechanism underlying the beneficial effects of skipjack-elastin hydrolysate, a food-derived elastin peptide in the human blood was screened. Consequently, Pro-Gly was identified. Pro-Gly enhances synthesis of elastin by human dermal fibroblast and the growth of human umbilical-vein endothelial cells. The results of the human trials and the occurrence of food-derived elastin peptide with biological activities in human blood indicate that fish-elastin hydrolysate is a promising food ingredient for improving skin and blood-vessel conditions.