High reproducible electrical bistability was observed and we deliberated its working mechanism through measurements of dynamic dielectric response in single organic layer sandwiched structure using top Ag electrode. The electrical transition between high-impedance state (OFF state) and low-impedance state (ON state) happened by the change of applied voltage patterns. Distinction between the OFF state and the ON state was not induced by change of static charge accumulation but reflected the difference of the response of mobile electric careers in the organic film. We proposed plausible working mechanism of transition from the pristine state to the bistable state. Namely, the electrical bistable state of our device is generated by penetration of Ag nanoparticles and creation of charge pathways across the organic film.