1. A method for surface-modifying a neural electrode, the method comprising: forming a neural electrode array; simultaneously electrode-depositing, on a surface of the neural electrode array, first and second metal nanoparticles having different solubilities with respect to an etching solution; and selectively etching the second metal nanoparticles using the etching solution, thereby forming a porous structure including the first metal nanoparticles on the surface of the neural electrode array.