A cationic cyanine dye, 1,1'-diethyl-2,2'-cyanine (PIC), was successfully intercalated into Na2Ti3O7 by a guest-exchange method using a propylamine/Ti3O7 intercalation compound as the intermediate, Based on the XRD and chemical analytical results, it was presumed that PIC was densely packed in the interlayer space with the short axis of its quinoline-ring almost perpendicular to the host layer. Spectroscopic results revealed that the PIC formed J-aggregates even in the restricted space between the titanate layers.