A membrane electrode assembly for a fuel cell, a method of preparing the same, and a fuel cell using the membrane electrode assembly for a fuel cell. The membrane electrode assembly includes an anode comprising an anode substrate, an anode diffusion layer, and an anode catalyst layer having pores; a cathode comprising a cathode substrate, a cathode diffusion layer, and a cathode catalyst layer having pores; and an electrolyte membrane interposed between the cathode and the anode, wherein the anode diffusion layer is hydrophilic and the cathode diffusion layer is hydrophobic, and the average diameter of the pores of the anode catalyst layer is smaller than the average diameter of the pores of the cathode catalyst layer. In the membrane electrode assembly, air can be easily supplied to the cathode and water can easily flow out of the cathode, thereby obtaining high performance of the membrane electrode assembly, and the anode catalyst layer has relatively small pores, thereby improving durability of the anode and reducing the diffusion speed of methanol in the anode catalyst layer to maintain the initial performance of a battery for a long time.