A method of manufacturing a catalyst for a Pt.sub.xM.sub.y-based PEMFC, M being a transition metal, including the steps of: depositing Pt.sub.xM.sub.y nanostructures on a support; annealing the nanostructures; depositing a Pt.sub.xM.sub.y layer at the surface of the nanostructures thus formed; and chemically leaching metal M. It also aims at the catalyst obtained with this method.

A photocatalyst has a perovskite type crystal, the photocatalyst has, present on a surface, a stepped structure including a terrace and a step, and an occupancy ratio of a projected area of the stepped structure to a total projected area in an observation image of the surface is 20% or more. It is preferable that the terrace is formed of a {100} facet, and the step is formed of the {100} facet or a {110} facet.