Recently, several reports demonstrated the efficacy of neoadjuvant chemotherapy (NAC) or chemoradiotherapy (NACRT) for patients with borderline resectable (BRPC) and locally advanced unresectable pancreatic carcinoma (LAPC). The aim of this study was to evaluate the treatment response after NACRT, especially for nerve plexuses, and the optimal resection area for superior mesenteric artery nerve plexuses in BRPC and LAPC patients after NACRT.A total of 17 patients with BRPC and LAPC received preoperative gemcitabine-based NACRT. The numbers of BRPC and LAPC patients were 13 and 4, respectively. We evaluated nerve plexus invasion by CT before and after NACRT, decided on the resection area of plexus invasion in SMA before NACRT, and compared the preoperative evaluation and clinicopathological findings.In the plexus of the supra-mesenteric artery (pl-SMA), arterial nerve plexus invasion, in cases <90°, all patients showed the absence of residual cancer in the resected specimen after NACRT. In cases between 90° and 180°, 1 of 2 patients (50%) showed nerve plexus invasion. In cases over 180°, all patients showed nerve plexus invasion. We could perform R0 resection in all 10 cases, and pl-SMA invasion disappeared in 6 of 7 BRPC patients.We demonstrated the relationship between the angle of nerve plexus tumor invasion and treatment effect after NACRT. We could perform R0 resection in all pl-SMA invasion cases, deciding on the resection area of pl-SMA based on CT before NACRT.