We describe a case of pulmonary lymphangiomyomatosis (LAM) with chylothorax that developed in a 46-year-old Japanese woman. This patient exhibited clinical symptoms of dyspnea and chest X-ray showed right pleural effusion. Thoracocentesis demonstrated chylous effusion. Chest computed tomography (CT) scan revealed multiple cystic lesions. Subsequent thoracoscopy revealed the chylorrhea from swelled vessels on the diaphragm. The clinical diagnosis, based on histological examinations with biopsy specimens obtained by thoracoscopy, was pulmonary LAM. Although the hormone therapy was not effective, chylous effusion was improved by the pleurodesis. Pulmonary LAM developing chylothorax is rare in Japan.