A methanol oxidation catalyst is provided, which includes nanoparticles having a composition represented by the following formula (1): Pt.sub.xRu.sub.yMo.sub.zT.sub.u (1)In the formula (1), the T-element is at least one selected from the group consisting of W and V, x is 20 to 80 at. %, y is 10 to 60 at. %, z is 1 to 30 at. % and u is 1 to 30 at. %. The area of the peak derived from oxygen bond of T-element is 80% or less of the area of the peak derived from metal bond of T-element in a spectrum measured by an X-ray photoelectron spectral method.