Porphyrins are the collective term for macrocyclic compounds and their derivatives, composed of four pyrrole rings linked on the α position through four methine groups. The central nitrogens form a stable complex with various metals such as iron, magnesium and cobalt. These metal complexes play important roles in biochemical processes. Metal porphyrin derivatives such as hemoglobin, vitamin B12, chlorophyll and cytochromes exist in living organisms. From the point of their specific optical and redox characteristics, their applications to solar cells or catalysts for chemical reactions have been studied.