Polyquinonediimines (PQDI) which have stable structure on heat and contains mono-azobenzene in the side chain were synthesized by means of condensation polymerization under TiCl$_4$. The synthesized monomers and polymers were identified by FT-IR, $^1$H-NMR, and elementary analysis. Especially, PQDI was comfirmed by the double-bonding peak of >C=N appeared near 1625 $cm^{-1}$ / by means of FT-IR spectrum. PQDI containing mono-azobenzene group in both side chains wat not soluble in non-polar solvents at all but partially soluble in the polar solvents having small dielectric constant, and dissolved in the strong acid such as sulfuric acid and $CH_3$SO$_3$H. Molecular weight distribution of PQDI measured by GPC showed 1.74. It was confirmed through X-ray diffraction analysis that the polymer was partially crystalline at the low angle region, but amorphous after heat treatment at 1$25^{circ}C$. The glass transition temperature (T$_{g}$ ) of synthesized polymer was measured as 1$25^{circ}C$ by differential scanning calorimetry. The SHG value for $chi$$^{(2)}$ after poling at 1$25^{circ}C$ was 8.6 pm/V (λ=1.542 ${mu}{ extrm}{m}$). The SHG value slowly decreased with time from the start but appeared temporal stability after 100 hours.