Two-dimensional (2D) photonic crystals composed of polymer pillar arrays were fabricated by a nanoimprinting process using ordered anodic porous alumina molds. The obtained 2D polymer photonic crystals exhibited a clear stop band in the visible wavelength region, which originated from the periodic pillar arrays. The position of the stop band could be controlled by changing the geometrical structure of the anodic porous alumina mold. The process allows the high throughput production of 2D photonic crystals, which are required for the preparation of various types of functional optical devices.