To provide a method for fitting a packing material to a base material surface capable of being utilized when manufacturing a member such as a separator or an electrolytic membrane used for a solid polymer fuel cell and provided with the packing material on a surface peripheral edge section.

The packing material 2 is fitted at least to one-side surface of the base material 1 in this method. A recessed groove 31 corresponding to the outer shape of the packing material 2 is thermally molded on a plastic sheet 3 having rigidity, and a prescribed quantity of a raw material 21 of the packing material is filled in the recessed groove to form the packing material of the prescribed shape. The packing material is fayed and transferred to the base material surface, then the plastic sheet 3 is peeled off by this method for fitting the packing member to the base material surface.