Ulcerative colitis (UC) is associated with a number of extraintestinal manifestations (EIMs) that may affect most organ systems. Among the EIMs, those involving the lung are rare. We report a case of pulmonary involvement and pyoderma gangrenosum in a patient with refractory UC. A chest computed tomography showed multiple nodular infiltrates in bilateral lungs. The patient had no respiratory symptoms. No infectious agents were detected. A transbronchial biopsy specimen showed nonspecific features. Prednisolone was initiated with significant improvement in the patient's abdominal symptoms and pyoderma gangrenosum. Subsequent imaging after steroid therapy showed improvement of the pulmonary infiltrates. The patient's abdominal symptoms relapsed when prednisolone was tapered. The patient subsequently received a proctocolectomy. Chest radiographs have shown resolution of pulmonary infiltrates. Because pulmonary involvement follows an independent course and a proctocolectomy may not be protective against a recurrence of pulmonary involvement, a careful follow-up should be continued.