A 27-year-old man was admitted to hospital for the investigation of hemosputum. He is a serving member of the Japan Self-Defense Forces. Chest radiography showed absence of the right hilar component, and the ipsilateral hemithorax was smaller than that of on the left side. Pulmonary arteriography demonstrated complete absence of the right pulmonary artery. Right cardiac catheterization did not show any concomitant cardio-vascular malformation. Therefore, this case was diagnosed as an isolated absence of the right pulmonary artery. Bronchial arteriograms demonstrated showed vascular enlargement and proliferation of the right bronchial artery. Bronchofiberscopic examination showed obvious bronchial mucosal vascular enlargement with submucosal eruption and swelling of the right bronchi. We also re-examined the chest radiographs of this patient from the previous 9-years. Those revealed a chronological decrease of the right lung volume and an increase of the cardio-thoracic ratio. Isolated absence of the right pulmonary artery is generally considered to have preferable survival, but close observation is necessary to monitor the pulmonary hemodynamics.