An injection molding technology is developed to replicate pillars in micro/nano scale on the thin plastic substrate. Two types of pillar are to be replicated and one is square type of 10um x 10um, the other is circular type whose diameter is in range of 100 nm ~ 300 nm. For both types of the pillars, the height is about 250 nm. A pattern master is first fabricated on the photo resist(PR) layer spin coated to about 250nm of thickness on chrome/quartz plate by patterning e-beam writing and then developing the PR. The patterns on the PR master are transferred by nickel electro-plating to fabricate rigid nickel stamper. Using this nickel stamper, a substrate with nano pillars on its surface is injection molded by optimizing the conditions to fabricate DNA separating chip.