In order to investigate the effect of hydrogen bonding formed between carboxylic acid groups on thermal properties of the side chain type liquid crystalline polymers, we synthesized the side chain type copolymers composed of a mesogenic monomer and a non-mesogenic monomer with carboxylic acid group. Hydrogen bonding was examined by thermally controlled FT-IR measurements. A mesophase was exhibited for the copolymers containing the mesogenic monomer above 40∼65 mol%. The mesomorphic temperature range(MR) of the copolymers increased in the order of the copolymer with methacrylic acid monomer, with benzoic acid monomer containing a flexible spacer and with benzoic acid monomer. This difference in the MR of the copolymers was demonstrated by FT-IR quantitative analysis of the area of the peak assigned to the dimer structure of the carboxylic acid group.