Among the various radioactive materials, Cesium is a major source of radioactive contamination and known to be the most dangerous radioactive material, can cause enormous damage to the ecosystem environment when released into the environment. Prussian Blue has been used as an adsorbent to effectively remove cesium, however it has the problem of being difficult to separate in water. In this study, carbonyl iron(CI) which is known as ferromagnetic synthesized with PB to solve the problem of PB particles. CI was used as a support of Ferromanetic Prussian blue Composite (FPC) and FPC can remove the cesium in water and be easily separated by self-separation phenomenon. The optimal cesium removal efficiency was confirmed under the injection conditions of 60g of CI particles through experiments to find the optimal mixing ratio of CI particles and PB. The removal rate of cesium was 95.4%. The FPC prepared through this study has excellent cesium removal capacity, and it can be completely separated from water when used directly in the cesium treatment field.