A method for manufacturing a fuel cell which includes layering and compression molding at least one of each of: thermoplastic resin sheets (A) containing 130 to 3,200 parts by weight of a carbonaceous material per 100 parts by weight of a thermoplastic resin; and thermoplastic resin sheets (B) containing 3 to 280 parts by weight of a carbonaceous material per 100 parts by weight of a thermoplastic resin, 50% to 100% by weight of the carbonaceous material being fibrous carbon. The thermoplastic resin sheets (A and B) are compression molded at a temperature 60° C. higher than the higher of the melting points of the two types of sheets such that the ratio between the final thickness (dA) of the compressed first thermoplastic resin sheet(s) (A) and the final thickness (dB) of the compressed second thermoplastic resin sheet(s) (B) satisfies the relation dA/dB≧2.