NOVELTY - An electrode for fuel cell comprises an electrode substrate including a conductive substrate and a carbon particle; and a catalyst layer disposed on the electrode substrate, where the electrode substrate comprises a pore with an average diameter of 20-40 mu m and porosity of 30-80 vol.% based on a total volume of the electrode substrate.    USE - As electrode used in membrane-electrode assembly for a fuel cell; in fuel cell system (claimed), used for generating power for producing electricity.    ADVANTAGE - The electrode substrate may include pores, and thus, improves performance of a fuel cell by controlling a pore size and porosity. In other words, when a membrane-electrode assembly operated under a low humidifying condition has a pore size and porosity within a particular range, the pore may not only improve material transmission due to capillary effects but also improve water retention characteristic due to surface area and surface tension increases. The electrode has excellent water retention capability under non-humid conditions, and thus, may improve over-all a fuel cell performance.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) membrane-electrode assembly for a fuel cell, comprising an anode and a cathode formed facing each other; and a polymer electrolyte membrane disposed between the anode and the cathode, where at least one of the anode and the cathode comprises the electrode; and    (2) fuel cell system comprising a fuel supplier configured to supply mixed fuel of fuel and water, a reforming part in fluid communication with the fuel supplier and configured to reform the mixed fuel to generate hydrogen, a stack in fluid communication with the reforming part, where the stack includes the electrode, where the stack is configured to generate electric energy by performing an electrochemical reaction between the hydrogen gas supplied from the reforming part and an oxidizing agent; and an oxidizing agent supplier configured to supply an oxidizing agent to the reforming part and to the stack.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of electrode for fuel cell.