Intercalation of an ammonium amphiphile having an azobenzene chromophore, 4-dodecyloxy-4 ‘-(trimethylammoniopentyloxy)azobenzene and 4-(ω-trimethylammoniodecyloxy) -p’- (octyloxy)azobenzene bromide, into the layered silicate magadiite (ideal formula Na2Si14O29·nH2O) was carried out by a conventional ion exchange reaction in an aqueous medium. An intercalation compound with the ideal formula {(C12AzoC5N+)1.4H0.6·Si14O29·nH2O} was obtained. Based on the change in the basal spacing (to 4.21 nm) after the reaction and the visible absorption spectrum of the product, the intercalated azo dyes appear to form a J-aggregate in the interlayer space of magadiite. Under UV and visible light irradiation, the intercalated azo chromophore exhibited reversible transcis isomerization in the interlayer space of magadiite. This is the first successful report of photochemical reactions of guest species in the interlayer space of magadiite.