Recently the electrical switching of magnetization and magnetic properties have been attempted by many researchers for the application to practical devices. This review introduces a significant magnetic response of Prussian Blue (PB) thin film incorporated in an ionic-liquid electrolysis cell by applying a DC bias voltage. Electrochemical hole doping into the PB film oxidized Fe^II to Fe^III ions in the film, providing quasi-reversible electrochromic behaviour. We performed magnetic measurements of the electrolysis cell under a DC bias on an SQUID magnetometer. The switching of the film from a paramagnet to a ferrimagnet with a magnetic response at low temperatures and an in situ enhancement of magnetization of the film at 300 K were demonstrated.