GAS DIFFUSION ELECTRODE BASE MATERIAL AND PRODUCTION METHOD THEREFOR, AND SOLID POLYMER FUEL CELL

In a microporous layer of the present invention, a fuel cell with high productivity, high power generation performance and high durability can be obtained. The present invention is a gas diffusion electrode base material having a microporous layer on one side of an electrically conductive porous base material, the electrically conductive porous base material contains carbon fiber and resin carbide and has a density of 0.25 to 0.39 g/cm3 and a pore mode diameter in a range of 30 to 50 µm, and the microporous layer contains a carbonaceous powder and a fluororesin and has a surface roughness of 2.0 to 6.0 µm, a porosity of 50 to 95%, and a pore mode diameter of 0.050 to 0.100 µm.