In the rising process of electro-optic effect by an applied electric field, Blue phases are enforced from the optically isotropic state to the optically anisotropic state. On the other hand, in the decay process of the electro-optic effect by the restoring force, BPs turn back from the optically anisotropic state to the optically isotropic state. The dielectric anisotropy of dual frequency liquid crystal (DFLC) changes from positive to negative as increasing the frequency of the electric field. If we apply the electric field with high frequency in decay process, it is expected that the response becomes faster. In this study, we investigated electro-optical properties of novel BPs consisting of DFLC.