Abstract: 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 the moldability is made excellent so that a light and compact configuration that is preferred in the automobile use or the like can be realized.