AbstractWe investigated the correlation between the surface roughness and the magnetic properties in electroplated Ni–Fe Permalloy thin films. The Ni–Fe Permalloy thin films electroplated with electrolytes containing a leveling additive showed reduction of coercivity and increase of permeability compared with those prepared with pure inorganic electrolytes. The decrease of the surface roughness resulted in the reduction of coercivity and showed a strong correlation. The improvements in the surface roughness and coercivity caused the initial and incremental permeability increase by 450% and 130%, respectively. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)