A purification device is provided. The purification device includes: an injection channel having an inlet provided on one end thereof; a purification channel and a discharge channel which branch off from the other end of the injection channel via a mesh part, and the remaining substance to be purified is discharged through the discharge channel; an ion-selective membrane contacting at least one side of the mesh part; and a buffer part arranged on the other side of the ion-selective membrane which is in contact with the mesh part, wherein the mesh part has an ion-selective coating layer formed on the surface thereof, and when an electric field is applied, an ion concentration polarization phenomenon occurs to the other end of the injection channel and to the adjacent portion of the mesh part, whereby an ion depletion zone is formed.