is one of the endogenously formed porphyrins and is synthesized in the heme biosynthetic pathway (1). PpIX is known to be a photosensitizing agent. It is excited by light and transfers the energy to molecular oxygen, resulting in formation of singlet oxygen. Singlet oxygen is a sort of active oxygen species and is highly reactive with various chemical compounds (2). PpIX is then expected to be usable as a herbicide, disinfectant, and so on. In the medical field, in particular, PpIX has also been used as a photosensitizer in photodynamic therapy (PDT) for tumor tissues (3-5). In PDT, photosensitizing agent located in tumor tissues are excited by light of a specific wavelength and generates cytotoxic singlet oxygen, leading to a sequence of photochemical and photobiological processes that cause irreversible photo-135