Sarcoid-like granulomatosis is a unique immune-related adverse event (irAE) in cancer patients treated with immune checkpoint inhibitors (ICIs). This irAE is infrequent, reported to range from 2% to 22.2% of melanoma treated with ICI. In a case of granulomatosis localized in the lung, it is difficult to differentiate granulomatosis from cancer progression or metastases. Herein, we report a case of ICI-induced sarcoid-like granulomatosis of the lung, which was confusable with localized recurrence of the primary lung cancer. A 56-year-old woman with c-stage IIIA of pulmonary squamous cell carcinoma in the right lower lobe received chemo-radiotherapy with two courses of cisplatin and vinorelbine and concurrent thoracic irradiation, followed by 1-year durvalumab consolidation therapy. The tumor in the right S6 grew and presented abnormal uptake by fluorodeoxyglucose positron emission tomography (FDG-PET), 1.5 years after durvalumab. Neither computed tomography (CT) nor FDG-PET found mediastinal and distant metastases. She underwent right lower lobe lobectomy. Histopathologically, the tumor and sampled lymph nodes contained no residue of carcinoma cells but presented diffuse epithelioid granuloma with infiltration of inflammatory cells, partial necrotic lesions and many multinucleated giant cells. In immunohistochemical stains, CD3+ and CD8+ T cells predominantly infiltrated, while there were few CD4+ T cells and a small number of CD20+ B cells. We followed her without steroid and other immunosuppressant drug. We should pay attention to the development of sarcoid-like granulomatosis as a rare irAE, which is difficult to be differentiated from cancer progression.