We have developed an optically isotropic liquid crystal composite which is optically isotropic on the macroscopic scale but has a short-range anisotropic order on the microscopic scale. In this state, the large Kerr effect and the fast electro-optical response have been observed . One of the important problems is non-zero birefringence after an electric field is applied and switched off, despite of the fact that birefringence is nearly zero before an electric field is applied. When the photo-polymerization was done through the filter having cut-off wavelength less than 390 nm, the resulted cell showed symmetrical CV response, suggesting symmetric distribution of generated polymers. The residual birefringence after applying electric field was successfully suppressed in the cell prepared by photo-irradiation through the cut-off filter. Thus the optically isotropic LCs with high contrast of electro-optical response was actually obtained.