Abstract: A device for the purification of synthetic oligonucleotides, characterized by comprising means for switching between purification with an affinity column which recognizes trityl groups, in cases where trityl groups are bonded, and purification with a disposable stepwise reverse phase chromatography column in cases where no trityl groups are bonded. The device makes it possible for any person to easily perform high-degree purification, simply by setting the synthesized oligonucleotides. Furthermore, it accomplishes both a method using an affinity column cartridge and a method for purification by HPLC.