A 72-year-old woman underwent a close examination because of chest computed tomography (CT) scan revealed a nodule in the left lower lobe of the lung. Positron emission tomography( PET) showed strong accumulation of fluorodeoxyglucose (FDG) in the lesion. Since lung cancer was strongly suspected, video-assisted thoracoscopic lung biopsy was performed. The lesion was diagnosed as organizing pneumonia by pathology. PET is widely used to distinguish between benign and malignant lung nodules, but FDG accumulation can also be seen in benign diseases such as inflammatory lesions. Abnormal accumulation can also be seen in organizing pneumonia, but strong FDG accumulation such as in this case is relatively rare, and it was difficult to distinguish it from lung cancer.