A novel cationic porphyrin bearing flexible omega-ammonioalkyl side chains, TMAP-Cl was prepared in high yield by using the K10 method. It was found that TMAP-Cl can be quantitatively ion-exchanged into interlamellar spaces of Mont, Sapo, and Hecto without suffering any protonation to the porphine ring. Especially, in the TMAP-Mont intercalation compound, the interlamellar distance was expanded to 10 Angstrom, which implies that a porphine ring in TMAP is installed upright rather than parallel to the clay surface.