A nozzle plate assembly of micro-injecting device and a method for manufacturing the same in which a master plate which defines a nozzle region is dipped into an electrolyte in which NiH2/SO3/H, NiCl2, H3BO3, C12H25SO4/NaS and deionized water are mixed in a predetermined ratio. Then, current having a predetermined density is applied several times, to thereby form a nozzle plate having a plurality of nozzles. The nozzle plate so formed has different roughnesses at inner and outer surfaces, to thereby eliminate ink-crosstalk and the generation of air bubbles in the ink feed channel.