In order to attain excellent electrical conductivity and molding processability, a fuel cell separator to be produced by performing press molding on a preform in which expanded graphite is used as the main raw material is improved so that the preform is produced by a papermaking method, whereby the characteristics of the mechanical strength, the flexibility, and the gas impermeability are improved, and a light and compact configuration that is preferred in the automobile use or the like can be realized. In a fuel cell separator which is to be produced by performing press molding on a preform 14 that is formed into a plate-like shape, with a molding die, therefore, the preform 14 is configured into a sandwich structure where a second sheet 14B in which a phenol resin is applied to graphite is interposed between a pair of first sheets 14A made by impregnating a sheet-like member with a phenol resin, the sheet-like member being obtained by a papermaking process using a raw material in which a fibrous filler is added to expanded graphite.