A novel adsorption medium containing selective molecular recognition site for one of the powerful cyanobacterium toxins, Cylindrospermopsin (CYN) was developed using a special technique, namely interval immobilization technique. The adsorption medium was prepared using molecular assembly derived from an alternative-template molecule coupled with functional monomers for fixing the interval between the ionic functional groups in CYN. As results of liquid chromatographic evaluations, selective molecular recognition ability for CYN was observed as expected. Further studies proved that the association constant for CYN on this medium was slightly higher than that on blank polymer.