The electrodeposition of Ag was studied in several ionic liquids. When the potential applied more negative than -0.25 V vs Ag/Ag(I), current density reached the diffusion-controlled region. The surface morphology of electrodeposited Ag changed depending on the applied potential. This result indicates that the applied potential affects the processes of Ag electrodeposition under diffusion-controlled region. Surface morphology was considered related closely to the crystal growth process. Since the electrode reaction rate is controlled by diffusion, the change of the surface morphology may be caused by the change of the double layer structure, which is expected to depend on the applied potential.