Conductive carbonaceous-fiber sheet and solid polymer electrolyte fuel cell

A conductive carbonaceous-fiber sheet has a thickness of from 0.05 to 1 mm, a weight per a unit area of from 60 to 250 g/m, a bending resistance (L) as determined by the 45 DEG Cantilever method of 6 cm or higher and an in-plane volume resistivity of 0.2 OMEGA cm or lower, and is suitable for use as a gas diffusion layer in a solid polymer electrolyte fuel cell.