Cunninghamella bertholletiae, a rare causative agent of human deep seated mycosis, has been reported with increased frequency in the Western countries, in recent years. We experienced a case of Cunninghamella bertholletiae pulmonary infection in a 63-year-old male with pulmonary fibrosis and mild diabetes mellitus. In spite of intensive anti-fungal chemotherapy following clinical diagnosis, he died of exacerbation of the underlying diseases. Postmortem examination showed Cunninghamella infection in the cavity of the lung and massive pulmonary fibrosis. There was no fungal invasion outside the cavity. This is the third report of Cunninghamella human infection in Japan.