Pneumonitis during durvalumab consolidation therapy after chemoradiotherapy (CRT) is a major cause of treatment discontinuation. Although previous studies have revealed an association between antinuclear antibody (ANA) positivity and the safety and efficacy of immune checkpoint inhibitors in advanced non-small cell lung cancer (NSCLC), there are no reports on durvalumab consolidation therapy. This study investigated the safety and efficacy of durvalumab after CRT in ANA-positive patients. We retrospectively reviewed patients with unresectable NSCLC treated with durvalumab after CRT between August 2018 and July 2022 at our institution. We evaluated the association among ANA positivity, treatment-related adverse events (AEs), and survival outcomes. Overall, 80 patients were enrolled, 39 of whom were ANA-positive. Although there were no significant differences in the incidence of each AE of any grade, ANA-positive patients tended to have a higher frequency of pneumonitis of grade 3 to 5 than ANA-negative patients (12.8% vs. 2.4%, p=0.104). ANA-positive patients had a significantly shorter median progression-free survival (PFS) and overall survival (OS) than ANA-negative patients [14.9 months vs. not reached (NR), p=0.005; NR vs. NR, p=0.013]. Multivariate analysis revealed that ANA positivity was an independent predictor of shorter PFS (HR=2.23; 95% CI=1.16-4.29; p=0.016) and OS (HR=2.28; 95% CI=1.01-5.12; p=0.046). ANA-positive patients receiving durvalumab after CRT tended to have a higher frequency of severe pneumonitis and significantly worse PFS and OS compared with ANA-negative patients.