Disclosed is an electrode catalyst for fuel cells, achieving enhanced utilization efficiency of the catalyst. Also disclosed are an electrode for fuel cells by use of the catalyst and a fuel cell. The electrode catalyst for fuel cells is featured in that a compound having at least one functional group and at least one proton-accepting group in the molecule is adsorbed onto a metal catalyst, and the functional group being partially or wholly constituted of a sulfur element or a nitrogen element as its constituent atoms.