Undifferentiated carcinoma of the pancreas (UDC) is rare and has a dismal prognosis. Here, we report a case of 6-year disease-free survival with a mixed type of UDC and UDC with osteoclast-like giant cells, with a high mitotic index as well as perineural, lymphatic, vessel, and diaphragmatic invasion. The patient underwent radical distal pancreatectomy and was subsequently treated with adjuvant chemotherapy using gemcitabine plus S-1 followed by maintenance chemotherapy with oral tegafur-uracil. The patient has been doing well with no evidence of recurrence for more than 6 years after surgery.