Mesogenic and azo monomer were synthesized and copolymerized to get liquid crystalline copolymer such as polymethacrylate (CP I). Another copolymer (CP II) was prepared with methylmethacrylate using the same azo monomer used above. Trans-cis isomerization of two copolymers was observed under UV-irradiation, The stability of photoinduced birefringence in CP I was found better than that of CP II.