A catalyst particle having high oxygen reduction reactivity and low methanol oxidation reactivity, a supported catalyst comprising the catalyst particle, and a fuel cell using a cathode comprising the supported catalyst are provided. The whole catalyst particle or at least the surface of the catalyst particle includes an alloy of two or more metals selected from the group consisting of Fe, Co, Ni, Rh, Pd, Pt, Cu, Ag, Au, Zn, and Cd. The alloy has a stronger oxygen-binding force than platinum or a weaker hydrogen-binding force than platinum.