Core-shell catalyst and reaction acceleration method

Provided are: a catalyst having a core-shell structure indicating high activity in an oxygen reduction reaction which is a cathode reaction of a fuel cell; and a reaction acceleration method using the catalyst. This core-shell catalyst which accelerates an oxygen reduction reaction includes silver or palladium as a core material, and platinum as a shell material. The core-shell catalyst has a face-centered cubic lattice (110) surface in the surface of the catalyst.