Polymerization of alkyl diazoacetates [N2CHCO2R: R = Et (1a) and Me (1b)] mediated by PdCl2 in the presence of an amine gave poly(alkoxycarbonylmethylene)s [(CHCO2R)(n): R = Et (2a,b), Me (3a,b)] bearing an ester group on every carbon atom of their main chains. MALDI-TOF-MS analyses of the polymers 2a and 3b indicated that the degree of polymerization of the polymers extended up to nearly 100, The Pd-mediated polymerization of 1a and 1b in the presence of pyridine afforded the polymers quantitatively after reprecipitation from CHCl3 into n-hexane. A mechanism of the polymerization initiated with a Pd-assisted nucleophilic attack of an amine to the monomers is proposed.