A case of non-Hodgkin malignant lymphoma of the lung was presented with a review of Japanese literatures. A 53-year-old woman was referred to our hospital because of an abnormal shadow on the roentgenogram of mass screening, with neither subjective symptoms nor abnormalities in physical examinations. Laboratory tests showed normal values. The diagnosis of pulmonary malignant lymphoma was obtained by immunohistochemical examinations. She underwent a upper lobectomy of the left lung with lymph nodes dissection of the mediastinum. The histological immunohistochemical and diagnosis of the resected tumor was primary pulmonary B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) without regional lymph nodes involvement. She has been doing well without any signs of recurrence for 15 months after the operation.