A gas diffusion electrode has a microporous layer on at least one surface of an electroconductive porous substrate. The microporous layer has a first microporous layer in contact with the electroconductive porous substrate, and a dense layer in contact with the first microporous layer. The thickness of the dense layer is at least 1 μm. The average number density B of pores having a pore diameter of 0.15-1 μm in the dense layer is at least 1.3A, where A is the average number density of pores having a pore diameter of 0.15-1 μm in the microporous layer disposed on at least one surface of the electroconductive porous substrate.