Polymer Langmuir monolayers are an ideal model for two-dimensional (2D) polymer chains, but our understanding of them is still limited. Using atomic force microscopy, we have for the first time successfully visualized the polymer chain packings in amorphous polyisocyanide monolayers deposited on mica. The long polymer chains, which were partially forced to form hairpin-like conformations, were sophisticatedly packed in the 2D film without any chain stacking. The trend of the persistent lengths of the polymers in the 2D films fairly corresponded to those of 3D chains in solution. The molecular-level information provided by direct observations such as these will improve our understanding of polymers in 2D space.