The invention claimed is:1. A membrane-electrode assembly for fuel cells comprising:an anode;a cathode; anda polymer electrolyte membrane between the anode and the cathode,wherein at least one of the anode and the cathode comprises a porous support and a catalyst layer, the porous support disposed between the polymer electrolyte membrane and the catalyst layer,wherein the at least one of the anode and the cathode includes catalyst particles and a binder resin,wherein a portion of the catalyst particles and a portion of the binder resin are included in the catalyst layer,wherein the rest of the catalyst particles are disposed only in a first region of the porous support and the rest of the binder resin is disposed across an entire region of the porous support, such that there is a second region of the porous support where the binder resin exists but the catalyst particles do not exist, andwherein the second region is disposed between the first region and the polymer electrolyte membrane.2. The membrane-electrode assembly according to claim 1, wherein a ratio of a total thickness of the catalyst layer and the first region to a thickness of the second region is 1:1 to 10:1.3. The membrane-electrode assembly according to claim 1, wherein a content of the binder resin in the catalyst layer or the first region is 20 to 40% by weight with respect to the total weight of the catalyst layer or the first region.4. The membrane-electrode assembly according to claim 1, wherein a mean size of pores of the porous support is 300 nm to 100 nm,a mean particle diameter of the catalyst particles is 450 nm to 250 nm, anda mean particle diameter of the binder resin is 250 nm to 50 nm.5. The membrane-electrode assembly according to claim 1, wherein the porous support comprises an expanded polytetrafluoroethylene (e-PTFE) polymer.6. The membrane-electrode assembly according to claim 1, wherein the porous support comprises a nanoweb in which nanofibers are integrated in form of a non-woven fabric including a plurality of pores.7. The membrane-electrode assembly according to claim 6, wherein the nanofibers comprise any one selected from the group consisting of nylon, polyimide, polyaramid, polyetherimide, polyacrylonitrile, polyaniline, poly(ethylene oxide), polyethylene naphthalate, poly(butylene terephthalate), styrene butadiene rubber, polystyrene, polyvinyl chloride, polyvinyl alcohol, polyvinylidene fluoride, polyvinyl butylene, polyurethane, polybenzoxazole, polybenzimidazole, polyamide-imide, polyethylene terephthalate, polyethylene, polypropylene, a copolymer thereof, and a mixture thereof.8. The membrane-electrode assembly according to claim 6, wherein the nanoweb is manufactured by electrospinning.9. A method of manufacturing a membrane-electrode assembly for fuel cells comprising:preparing a composition including catalyst particles and a binder resin;applying the composition onto a porous support such that (i) a portion of the catalyst particles and a portion of the binder resin remains on the porous support, (ii) the rest of the catalyst particles permeate only to a partial depth of the porous support, and (iii) the rest of the binder resin permeate permeates to an entire depth of the porous support;in order to form an electrode sheet, drying the composition-applied porous support such that (i) a catalyst layer including the portion of the catalyst particles and the portion of the binder resin is formed on the porous support, (ii) the rest of the catalyst particles are disposed only in a first region of the porous support, the first region being in contact with the catalyst layer, and (iii) there is a second region of the porous support where the binder resin exists but the catalyst particles do not exist; andbonding the electrode sheet to a polymer electrolyte membrane in such a way that the second region is disposed between the first region and the polymer electrolyte membrane.10. A fuel cell system comprising:a fuel supply for supplying a fuel mixture of fuel and water;a modifier for modifying the fuel mixture to generate a modification gas including hydrogen gas;a stack comprising the membrane-electrode assembly according to claim 1 and generating electric energy by electrochemical reaction between the modification gas including hydrogen gas supplied from the modifier with an oxidant; andan oxidant supply for supplying the oxidant to the modifier and the stack.