A solid catalyst has a close-packed structure and has a first surface layer and a second surface layer, wherein the first surface layer includes platinum as a main component and the second surface layer contains Pt.sub.aX.sub.b (wherein X is one element selected from the group consisting of Zr, Hf, Nb, Ta, Mo, and W; a+b=100; and 25.ltoreq.b.ltoreq.50); and a fuel cell includes the solid catalyst as an anode-side electrode catalyst.