NOVELTY - An electrode substrate (10, 10') for a fuel cell, comprises a diffusion layer (1, 1'); a first microporous layer (2, 2') that is embedded into the diffusion layer, where a thickness of the first microporous layer is 10-30 microns; and a second microporous layer (3, 3') that forms a boundary with the diffusion layer, where second microporous layer is on the surface of the embedded first microporous layer.    USE - The electrode substrate i.e. anode or cathode electrode substrate is useful for a membrane-electrode assembly for use in a fuel cell (claimed) for producing electrical energy.    ADVANTAGE - The electrode substrate has improved performance such as increased diffusion properties of a fuel or an oxidant, increased properties of releasing moisture, and excellent electron conductivity.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) a method of preparing an electrode substrate for a fuel cell, comprising mixing carbon material, a binder, and a solvent to prepare a coating composition; coating the coating composition onto a diffusion layer; and firing the coated diffusion layer to form a first microporous layer that embeds into the diffusion layer, and a second microporous layer that forms a boundary with the diffusion layer; and    (2) a membrane-electrode assembly (100) comprising an anode (30') including an anode electrode substrate comprising an anode diffusion layer, a first anode microporous layer, a second anode microporous layer, and an anode catalyst layer (20') provided on the second anode microporous layer; a cathode (30) comprising a cathode electrode substrate comprising a cathode diffusion layer, a first cathode microporous layer, a second cathode microporous layer, and a cathode catalyst layer (20) provided on the second cathode microporous layer; and a polymer electrolyte membrane with opposing sides, the polymer electrolyte membrane interposed between the anode and cathode, with each side of the polymer electrolyte membrane respectively contacting the catalyst layers of the anode and cathode.    DESCRIPTION OF DRAWING(S) - The figure is a cross-sectional view showing a membrane-electrode assembly for a fuel cell.    Diffusion layer (1, 1')    First microporous layer (2, 2')    Second microporous layer (3, 3')    Electrode substrate (10, 10')    Cathode catalyst layer (20)    Anode catalyst layer (20')    Cathode (30)    Anode (30')    Membrane-electrode assembly (100)