As a side chain type of liquid crystalline polymer, the copolymers of cholesteryl methacrylate and butyl methacrylate were synthesized. When the mesomorphic behavior of the copolymers was examined with a polarized microscope, the observed transition temperatures were so much varied that the mesomorphic behavior had to be studied by thermal optical analysis (TOA). TOA curves with a single peak were obtained by a sandwich-type film prepared by interposing the casting solution between two cover glasses and drying sufficiently. The mesomorphic temperature region increased with increasing mole fraction of cholesteryl methacrylate (ChMA) in the copolymers. The appearing and clearing temperatures of birefringence shifted to the higher temperature side with increasing mole fraction. The effect of pretreatment of the cover glasses with trimethyl chlorosilane was examined. The relation between the maximum intensity of the TOA curve and the film thickness was studied for both films prepared with the treated and untreated glasses. The intensity remarkably increased with increasing film thickness for the treated glasses, but no such correlation was found for the untreated glasses. A sandwich cell was prepared by the same casting method of a TOA sample with tin coated glasses. The cell was heated up to the mesomorphic temperature under a dc field of 40 V. Although no electro-optical effect was observed in the first heating step, the apparent flow instability, similar to William’s domain, appeared in the cooling step from the isotropic state. Small angle X-ray diffraction patterns were obtained for the samples of both cast and annealed films. A sharp peak at 2θ=2.5° corresponding to 35.5 A of periodicity was observed only for annealed film.