Micropatterning of polymers by ion irradiation was demonstrated in this study. Various polymer thin films spin-coated on Si wafers were irradiated with proton ions through a pattern mask in a contact mode under various conditions. The irradiated films were baked and developed to generate polymer patterns. Well-defined 40 μm negative-type patterns were obtained using a 300-keV ion implanter. In the case of PMMA, both positive and negative patterns could be obtained by controlling the ion fluence.