The effect of an external magnetic field on the preparation of silver nanowires was studied. The silver nanowires were synthesized using solid electrolyte RbAg4l5 thin films by applying both a direct current (DC) electric field and a magnetic field. The RbAg4l5 thin films, which were prepared by deposition at room temperature and atmospheric pressure on a NaCl substrate, were used for the transfer of Ag+ ions between two Ag electrodes during the preparation process. When only the DC electric field is applied, the silver ions migrate toward the cathode. On the edge of the silver film at the cathode the Ag+ ions congregate to form aligned nanowires. If the magnetic field is also applied perpendicular to the DC electric field, the morphology of the nanowires can be controlled by rotating the sample in the magnetic field. Experimental results show that the growth of the silver nanowires is determined by the Ag+ ionic flux.