Three types of mono-, tri-, and penta-cationic antimony(V) porphyrin derivatives (Sb(V)Pors) were synthesized, and their photochemical properties on the anionic clay were systematically investigated. Sb(V)Por derivatives are dihydroxo(5,10,15,20-tetraphenyl-porphyrinato)antimony(V) chloride [(Sb-V(TPP)(OH)(2)]Cl-+(-)), dihydroxo[5,10-diphenyl-15,20-di(N-methyl-pyridinium-4-yl)porphyrinato]antimony(V) trichloride ([Sb-V(DMPyP)(OH)(2)](3+)3Cl(-)), and dihydroxo[5,10,15,20-tetrakis(N-methyl-pyridinium-4-yl)porphyrinato]antimony(V) pentachloride ([Sb-V(TMPyP)(OH)(2)](5+)5Cl(-)). The photochemical behaviors of three cationic Sb(V)Pors with and without clay were examined in aqueous solution. For all Sb(V)Por, aggregation behaviors were not observed in the day complexes even at high density adsorption conditions. The transition probabilities and fluorescence quantum yields of Sb(V)Por showed a tendency to be increased by the complex formation with day. The less cationic Sb(V)Por/day complex showed the larger fluorescence quantum yield. The more cationic Sb(V)Por/dy complex showed the longer fluorescence lifetime. These effects of complex formation with day on the photochemical properties of Sb(V)Pors were discussed using the molecular potential energy curves of the porphyrin ground state and excited state. It is conduded that two types of effects work in the Sb(V)Por/day system: effect i (structure resembling effect) is that the most stable structure becomes relatively similar between the ground and excited states, mainly by hydrophobic interactions between the porphyrin molecule and the day surface, and effect ii (structure fixing effect) is that sharpened potential energy curves of day complexes can lead to the increase of activation energy for the internal conversion from excited state to a high vibration level of ground state, mainly by electrostatic interactions between cationic porphyrin and anionic day. Like this, the unique effects of the day surface on the photochemical behavior of dyes were observed and the mechanisms were rationally discussed.