In the area of neurosurgical tumor diagnosis, clinical research on photodynamic diagnosis using 5-aminolevulinic acid (5-ALA) has already been undertaken, and the safety of 5-ALA has also been demonstrated. 5-ALA is approved in the diagnosis of brain tumor and bladder tumor by the Ministry of Health, Labour and Welfare. 5-ALA is a natural amino acid contained in a living body and is a precursor of hemoglobin. When absorbed into the body by oral ingestion, porphyrin synthesis by heme synthesis is specifically performed in a tumor-specific manner, and accumulation of fluorescent protoporphyrin IX (pp IX) is observed. However, pp IX is metabolized and disappeared in normal tissues. When tumor tissue is irradiated with excitation light, at the site where pp IX accumulates, it exhibits red fluorescence. We applied 5-ALA for photodynamic diagnostic in thoracic malignancies.