A 4-year-old boy with pancreatoblastoma was reported. He was admitted to our hospital with complaints of abdominal pain and abdominal distension. On admission hard mass was palpated below the left costal margin. Labolatory examinations revealed elevated serumAFP (1437.9ng/ml) .X-CT and US showed abnormal mass occupying left upper portion of the abdomen. This case was diagnosed preoperatively as malignant teratoma arising from the retroperitoneal cavity, and operation was performed. The tumor was successfully extirpated with the tail of the pancreas to which it closely adhered. The pathological specimen showed squamoid corpuscle surrounded by acinar like arrangement, so called organoid structure. According to the histological findings, the final diagnosis of pancreatoblastoma was made. Sixteen cases of pancreatoblastoma in children were reviewed from Japanese literatures. Cases with complete resection of the tumor without metastasis had good prognosis. Serum AFP was useful in many cases as a tumor marker for making diagnosis and following up patients in post operative course.