We report effects of magnetic field on electrical bistability of ferromagnetic quantum dots. Here, we select Fe3O4 nanoparticles that can be magnetized. Devices based on such nanostructures exhibit conductance switching. Upon application of a magnetic field, the nature of electrical bistability changes completely. From the comparison of electrical characteristics without and with a magnetic field, we comment that magnetization and conductance-switching to a high-state occur concurrently. We also show how a transition between the two types of electrically-bistable characteristics occurs. The results show the viability of data-storage applications in quantum dots through magnetic field. (C) 2010 Elsevier B.V. All rights reserved.