We report a case of cystadenoma of the pancreas that showed interesting findings on the preopeartively imaging diagnosis. While the patient, a 68-year-old man, was being treated as an inpatient in the department of internal medicine for cerebral infarction, he showed indications of having an abdominal tumor mass. A solid hyperechoic tumor was revealed by ultrasonography, and CT imaged the mass as a relatively homogeneous area of low density. A hypervascular tumor was found on angiography. Under a suspected diagnosis of tumor of the pancreatic body, particularly cystadenoma of the pancreas, laparotomy was undertaken for resection of the tumor, together with excision of the pancreatic body and tail. The tumor excised was 10×8×9 cm in size, weighed 490 g, and had a thin capsule, the surface of which was irregular and enriched in dilated tumor vessels. The tumor consisted of many small cysts, each of which was 2-4 mm in size. In the center of the tumor, there were cicatricial tissues which were radially fibrous. The tumor was histopathologically diagnosed as serous cystadenoma. This tumor is relatively rare, but shows characteristic findings on US, CT and angiography, leading to relatively easy diagnosis. The prognosis is favorable without malignant change, unlike mucinous cystadenoma.