Technology development associated with photodynamic therapy (PDT) comprised of photosensitizer, light source, and light delivery system becomes active recently by the development of photosensitizer and related technologies. Clinical applications of PDT are expanded gradually to the therapy for psoriasis, age‐related macular degeneration, diabetes, infectious disease and cancers occurring in various organs etc. Specifically advances in technology development of drug delivery system using nanotechnology have given photosensitizer with a high selectivity and therapeutic efficacy for target cell or tissue. This review is focused on studies investigating recent R&D trend and clinical applications of photosensitizer for photodynamic therapy and the understanding technology trend and position of major nations through paper reviews and patent analysis research.