We report here 3 cases of remnant pancreatic cancer after surgery for invasive ductal carcinoma. Case 1 was a 73-year-old male who underwent distal pancreatectomy(pap, pT3, pN0, M0): fStage II A(JPS 7th). He developed a remnant pancreatic cancer 39 months later, and total remnant pancreatectomy was performed. He died from sepsis 9 months after surgery. Case 2 was a 72-year-old female who underwent subtotal stomach-preserving pancreatoduodenectomy(SSPPD)(tub2, pT1c, pN1a, M0): fStage II B. She developed a remnant pancreatic cancer 82 months later. This lesion seemed to be resectable. But she hoped to take a best supportive care, and died 13 months after diagnosis. Case 3 was a 68-year-old female who underwent SSPPD(tub1, pT3, pN1a, M0): fStage II B. She developed a remnant pancreatic cancer 20 months later and was successfully treated by chemotherapy and carbon-ion radiotherapy.