Novel poly(cyclodiborazane)s containing transition metal in the main chain were synthesized by hydroboration polymerization between dicyano monomers including metal complexes and tripylborane. From gel permeation chromatographic analysis (THF, PSt standards), the number-average molecular weights of the obtained polymers were found to be 6,000. The polymers were soluble in common organic solvents and showed good stability toward air and moisture. The optical properties of these polymers were examined by UV-vis absorption and fluorescence emission measurements.