||Computed Tomography (CT) is a widely used imaging technique for ischemic stroke with high penetration depth, fine resolution, and short operation time. While conventional molecular CT contrast agents can locate the blocked blood vessel, it is impossible to know the exact size and shape of the clot. Nanoparticle-based contrast agents have shown the possibility of expressing the size and shape, still toxicity of accumulated nanoparticles was unknown. Therefore, we suggest a polymeric nanoparticle as biodegradable CT contrast agents. A water-soluble iodinated monomer was used with a biodegradable linker and degradation products were biocompatible. Imaging was successful showing not only the location but size and shape of the clot as well, even for a partially blocked blood vessel. In conclusion, we expect the polymeric nanoparticles work as biodegradable CT contrast agents capable of imaging the clot with exact size and shape.