This fuel cell gas diffusion layer has a conductive porous layer (21a) that is configured from: porous carbon, which is formed such that the porosity distribution thereof in the direction in which the fuel cell gas diffusion layer is laminated with a film electrode-bonded body (10) is substantially uniform; and a PTFE resin disposed by being diffused in the whole carbon. In the case where the ratio of the carbon surface exposed without being covered with the PTFE resin with respect to the carbon surface is defined as exposing ratio, the exposing ratio of the conductive porous layer (21a) on the cathode electrode (12a) side is higher than the exposing ratio of the conductive porous layer (21a) on the diffusion layer base material (22a) side.