A 69-year-old woman with no symptoms and no history of smoking was found to have a nodule in her right lung, which was detected on an annual X-ray examination. Chest computed tomography scan showed a solitary nodule in the right lower lobe. The nodule demonstrated a tendency to increase in size, suggesting it was lung cancer. She underwent a right lower lobectomy. Pathological findings showed histiocytes around the dilated bronchi and the cells were positive for CD1a and S-100 proteins, leading to the diagnosis of pulmonary Langerhans cell histiocytosis (PLCH). PLCH is a rare disease that occurs primarily among smokers and is characterized by proliferation and infiltration of Langerhans cells, eosinophils, and other inflammatory cells. PLCH is known as a diffuse lung disease and generally presents with granular and nodular shadows, and cysts in the upper and middle lobes. We report an extremely rare case of PLCH in a nonsmoker showing a solitary lung nodule.