The present invention provides a pancreas induced in vitro that is useful for developmental engineering and organ engineering, and a method wherein a pancreas induced in vitro which contributes to the development of diagnosis and treatment of pancreatic disorders for higher animals, can artificially and efficiently be induced from a gastrula apart from the presumptive region of pancreas. An explant which has a secretory gland-like structure wherein several cells are gathered and which expresses insulin is formed in vitro by treating the blastopore upper lip of an early gastrula of a vertebrate such as Xenopus with retinoic acid in vitro, and then culturing. The treatment with retinoic acid can be carried out, for example, by treating with retinoic acid at a concentration of 10.sup.-5 M or above for three hours.