Photochemical alignment change was examined for a nematic liquid crystal (5CB) and a smectic liquid crystal (12CB). The distinct critical value of electric field on the molecular orientation as observed for the smectic liquid crystal. The transformation from a homogenous alignment to a homeotropic alignment in the electric field was induced by trans-cis photoisomerization of azobenzene derivatives. The amount of cis-form required for the transformation of the molecular alignment was smaller than that for photochemically induced isothermal phase transition.