Regioregulated poly(aminopyridine)s were synthesized by a Pd-catalyzed C-N coupling reaction. The polymerization using Pd(0) and a bulky monodentate phosphine ligand distinctively produced the para-linked and meta-linked poly (amino pyridine) s, without the need for a protection process. The regioregularity of the polymer was confirmed by H-1 NMR spectroscopy. Model reactions were studied to evaluate the possibility of crosslinkage in the polymer. A large difference in reactivity was observed between 5-amino-2-bromopyridine and 2-amino-5-bromopyridine, which should have afforded same product. Density functional theory (DFT) calculations indicated that electron he densities of the Br-bound carbon atom and pyridine-nitrogen atom determine the reactivity of the monomers.