Lepidocrocite-type titania nanosheets (TNSs) with composition Ti0.89O2 were newly designed and synthesized. The densely packed TNS surface on glass substrates (TNS-LB) was fabricated by the Langmuir-Blodgett method. The adsorption behavior of a cationic porphyrin (p-TMPyP4+) dye onto TNS suspension (TNS-SUS) and TNS-LB was examined. High density without an aggregation assembly structure of p-TMPyP4+ was observed in the TNS-LB/p-TMPyP4+ complex. The average intermolecular distance is 2.3 nm. This is the first example indicating that the size-matching effect is effective for semiconductor nanosheets.