For inflammatory bowel disease (IBD), antitumor necrosis factor treatment offers a new direction for both patients and medical doctors. This treatment has dramatically improved the quality of life for patients with ulcerative colitis and Crohn disease (CD). However, with increasing usage and longer follow-up periods, a wider range of possible adverse effects may be encountered. We report an unusual case of pulmonary sarcoidosis developed during the treatment of a patient with CD by using infliximab. A 30-year-old male who had been treated for CD with infliximab for 18 months was admitted due to abnormal opacities on chest radiography. Chest computed tomography displayed clustered small nodules in both lobes and enlarged multiple lymph nodes. The patient was diagnosed with sarcoidosis from the results of a biopsy of the subcarinal lymph node. Lung lesions were improved five months after infliximab was stopped.