The patient was a male in his 60s who presented with obstructive jaundice and was diagnosed with pancreatic head cancer. He was referred to the Department of Surgery 2 months later due to prolonged jaundice and immediately underwent pylorus-preserving pancreatoduodenectomy with the diagnosis of resectable pancreatic cancer. Pathology showed pN1b (14/37), but 16b1 interaorticocaval was 0/1. The patient was then diagnosed with Stage ⅡB, R0. After completion of adjuvant chemotherapy with S-1, 1 year after surgery, CA19-9 was reelevated and PET/CT-positive enlarged lateroaortic lymph nodes and multiple nodules in both lungs were observed. The lymph nodes were also seen on preoperative CT, and the preoperative diagnosis was Stage Ⅳ. After insertion of an implantable central venous port, mFOLFIRINOX therapy was initiated. The patient had an anaphylactic reaction after 7 courses of L-OHP, and the treatment was continued without L-OHP. After 40 courses of mFOLFIRINOX therapy, the aortic lymph nodes reduced in size, PET results were negative, and the pulmonary nodules partially resolved. We report a case of a patient with Stage Ⅳ pancreatic head cancer who maintained PR for more than 1 year and 7 months after the initiation of mFOLFIRINOX therapy and survived for more than 2 years and 10 months since the initial diagnosis.