Palladium-catalyzed amination of poly(p-bromostyrene) with 4-(phenylamino)azobenzene afforded polystyrene derivative having an aminoazobenzene group in the side chain with a high degree of substitution. Palladium-catalyzed polycondensation of aryl dibromides with I-aminoazobenzene also gave poly(iminoarylene)s having azobenzene group in the side chain in good yields. Photoinduced and thermal cis-trans isomerization behaviors of the polymers were investigated. Comparison of isomerization rate constants and activation energy values of the polymers and the corresponding model compound showed little difference in the kinetics data between the polymers, thus suggesting no significant influence of the structure of the polymer backbone on the azobenzene cis-trans isomerization. The absorption spectra of the polymers were dependent on the acidity of media because it can exist in neutral and protonated forms.