302 Background: The preoperative stage and intraoperative stage of gastric cancer were unified as the clinical stage in the 8th edition of the TNM classification (UICC). Although there are some reports about the relationship between preoperative stage and prognosis, the relationship between intraoperative stage and prognosis remains unclear. The aim of this study was to clarify the impact of intraoperative diagnosis and staging on long-term survival. Methods: Overall survivals were examined in 915 patients who underwent curative resection for gastric adenocarcinoma between April 2011 and March 2019 in our hospital. Results: The median age of the patients was 69 years (27-90 years), including 585 male and 330 female. The median follow-up period was 33.6 months (0.1-86.7 months). The number of the patients according to intraoperative stage were 641(70.1 %) in stageI, 15(1.6%) in stageIIA, 135(14.8%) in stageIIB, 111(12.1%) in stageIII, 12(1.3%) in stageIVA and 1(0.1%) in stageIVB. The hazard ratios of intraoperative stage for overall survival were as follows (ref: StageI); StageIIA, 6.990 (95% CI: 2.473-19.760, p < 0.001), StageIIB, 2.234 (95% CI: 1.220-4.092, p = 0.009), StageIII, 4.091 (95% CI: 2.416-6.928, p < 0.001), StageIVA, 6.061 (95% CI: 2.150-17.080, p < 0.001), StageIVB, 14.92 (95% CI: 2.035-109.3, p = 0.008). Conclusions: The survival of intraoperative StageIIA was poorer than StageIIB/III. Intraoperative positive lymph node metastasis could be negative impact of survival, even if tumor invasion was T1 or T2.