A laser-addressing rewritable optical information storage for (liquid crystalline side chain copolymer: LCcoP/low molecular weight nematic liquid crystals: nematic LCs/photo-responsive molecule: PM) ternary composite systems in a smectic state was investigated on the basis of a reversible and bistable electro-optical switching driven by ac electric fields with two different frequencies. In order to improve the response speed for the electro-optical switching for the ternary composite system, a LCcoP with the mesogenic side chain fraction of 52.5 mol% was synthesized. The ternary composite system with the LCcoP fraction of 36 wt% showed a smectic state over a wide range near room temperature. High speed reversible and bistable electro-optical switching (similar to 100 ms) under an appropriate electric field, and a stable memory effect (similar to y) were demonstrated upon irradiation of UV light of 355 nm by using a YAG laser for the ternary composite systems in a smectic phase at room temperature.