In a method for manufacturing Ni—Al alloy powders for electrode materials of fuel cells, in which, using aluminum chloride (AlCl3) as a catalyst, powders of Ni and Al, that have been used as electrode materials, are chemically reacted with each other to diffuse the Al into the Ni powders, so that Ni—Al alloy powders can be manufactured at a low temperature below fusion points of Ni and Al while maintaining a shape and a size of the existing Ni powders as they are, thus providing a manufacturing process of Ni—Al alloy powders that is simple, economical, compatible in working, and ready for scale-up, and in which a conventional manufacturing process of electrode based on Ni is used as it is, so that large sized electrode is manufactured.