Ectopic splenic tissue in the abdominal cavity is a common entity, with a reported incidence of 10% in the general population. However, an intrapancreatic accessory spleen is a rare disease, and moreover cyst formation in it is exceedingly rare. A 58-year-old woman with a 25-mm multilocular cyst in the tail of the pancreas detected incidentally by ultrasonography was admitted for further evaluation. Because malignancy could not be ruled out, a spleen-preserving distal pancreatectomy was performed. The cut surface of the surgical specimen showed a multilocular cyst surrounded by brown solid tissue resembling normal spleen. Pathological examination revealed it was stratified squamous epithelium and was surrounded by splenic tissue. The final pathological diagnosis was epidermoid cyst in an accessory spleen in the pancreas. This cyst has no characteristic features on diagnostic imaging. Consequently, it is not possible to make a definite preoperative diagnosis in most cases. Epidermoid cyst in intrapancreatic splenic tissue is another lesion to be considered in the differential diagnosis of pancreatic tail tumors.