NOVELTY - The fuel cell stack comprises stacked unit cells, a waterproof member (21a), a membrane-electrode assembly (11), a gas diffusion layer (12), and a gasket (14). The waterproof member is formed at an outer edge of a metallic bipolar plate (13) to seal a gap between joined surfaces of the metallic bipolar plate and formed by applying a waterproof liquid and a waterproof tape to the entire outer edges of the metallic bipolar plate, the membrane-electrode assembly, the gas diffusion layer and the gasket to cover the outer cut portion of each metallic bipolar plate.    USE - Used as a fuel cell stack, where the fuel cell such as a polymer electrolyte membrane fuel cell is useful for: electrical and electronic devices such as portable devices; industrial and household appliances; and motor vehicles such as passenger automobiles including sports utility vehicles, buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, hybrid vehicles, gasoline-powered and electric-powered vehicles and plug-in hybrid electric vehicles.    ADVANTAGE - The cost-effective fuel cell stack has improved corrosion resistance, and increases start-up time and reaction time of the fuel cells.    DETAILED DESCRIPTION - The fuel cell stack comprises stacked unit cells, a waterproof member (21a), a membrane-electrode assembly (11), a gas diffusion layer (12), and a gasket (14). The waterproof member is formed at an outer edge of a metallic bipolar plate (13) to seal a gap between joined surfaces of the metallic bipolar plate and formed by applying a waterproof liquid and a waterproof tape to the entire outer edges of the metallic bipolar plate, the membrane-electrode assembly, the gas diffusion layer and the gasket to cover the outer cut portion of each metallic bipolar plate. The gasket: is positioned from the outside of the waterproof member such that water vapor and moisture from the fuel cell stack are prevented from brought into contact with an outer cut portion of each metallic bipolar plate by the waterproof member; is interposed between adjacent metallic bipolar plates; is compressed by clamping force of the fuel cell stack to surround and completely seal the outer edges of the membrane-electrode assembly and the gas diffusion layer; and comprises a first airtight member interposed and compressed between the metallic bipolar plate and the membrane-electrode assembly or between the metallic bipolar plate and the gas diffusion layer to maintain the airtightness, and a second airtight member integrally formed with the first airtight member and compressed between adjacent metallic bipolar plates to surround and seal the outer edges of the first airtight member, the membrane-electrode assembly and the gas diffusion layer.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a fuel cell stack.    Membrane-electrode assembly (11)    Gas diffusion layer (12)    Metallic bipolar plate (13)    Gasket (14)    Waterproof members. (21a)