Oxide semiconductors with MCM-50--like layered structures are synthesized by liquid crystal templating followed by hydrothermal treatment. The band gap energy of hydrothermal-treated lamellar TiO$_2$ shows a substantial blue shift of $Delta E_g=0.31$~eV. The thickness of the 2-dimensional TiO$_2$ sheets estimated from $Delta E_g$ by using Blus' equation describing the quantum-confinement effect agrees within a factor of 1.5 with that determined from TEM observation. A new photoluminescence peak appears at $ca.$ 380~nm, being in good accordance with the wider band gap energy of the lamellar TiO$_2$. Lamellar Fe$_2$O$_3$ and Bi$_2$O$_3$ show sharp absorption peaks at the lower energy of the absorption edges, suggesting exciton absorption observable at root temperature.