NOVELTY - A polyelectrolyte fuel cell consists of an assembly (8) having an electrolyte layer (1) arranged between an anode (7) containing a gas-diffusion layer (6) formed on a catalyst layer (5), and a cathode (4) containing a gas-diffusion layer (3) formed on a catalyst layer (2), a anode separator (11) provided with a fuel gas flow path (13) in one main surface, and a cathode separator (10) provided with an oxidizing-agent gas flow path (12) in one main surface. A low-humid reactive gas is supplied to the fuel gas flow path and oxidizing-agent gas flow path.    USE - Polyelectrolyte fuel cell is used for electric-power generation in vehicles.    ADVANTAGE - The polyelectrolyte fuel cell prevents poisoning of anode by sulfur substances mixed with oxidizing-agent gas, even under low-humid conditions.    DETAILED DESCRIPTION - A polyelectrolyte fuel cell consists of a membrane electrode assembly having an electrolyte layer arranged between an anode containing a gas-diffusion layer formed on a catalyst layer, and a cathode containing a gas-diffusion layer formed on a catalyst layer, a tabular anode separator provided with a fuel gas flow path in one main surface, and a tabular cathode separator provided with an oxidizing-agent gas flow path in one main surface. The assembly is interposed between the main surface in which the fuel gas flow path is formed and the main surface in which the oxidizing-agent gas flow path is formed. A low-humid reactive gas is supplied to the fuel gas flow path and oxidizing-agent gas flow path. The hydrophilicity of cathode gas-diffusion layer in its portion opposite to an upstream portion which is a portion including an uppermost stream portion in the oxidizing-agent gas flow path is rendered lower than that of anode gas-diffusion layer in its portion opposed to the cathode gas-diffusion layer upstream region (3a) by rendering the hydrophilicity of anode gas-diffusion layer upstream opposed region higher than the cathode gas-diffusion layer upstream region over the entire region of anode gas-diffusion layer upstream opposed region.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of the polyelectrolyte fuel cell. (Drawing includes non-English language text)    Electrolyte layer (1)    Cathode catalyst layer (2)    Cathode gas-diffusion layer (3)    Cathode gas-diffusion layer upstream region (3a)    Cathode (4)    Anode catalyst layer (5)    Anode gas-diffusion layer (6)    Anode (7)    Membrane electrode assembly (8)    Cathode separator (10)    Anode separator (11)    Oxidizing-agent gas flow path (12)    Fuel gas flow path (13)