Fluctuation in contact resistance during sliding contact, an important indication of the contact interface condition, has been analyzed from the viewpoint of adhesive wear. An equation which is able to estimate the fluctuations in contact resistance was deduced, as the adhesive junction is considered to be the main electric current path. It was shown that fluctuations in contact resistance caused by adhesive wear can be estimated in terms of ( W/ P) − n and the properties of the contaminant films. Moreover, in metal transfer, which is important in dissimilar metal combinations, it was found that the nature of the transfer is determined by W ab / P and hardness. In the combination of metals with a high value of W ab / P and a large difference in hardness, a smooth stable sliding condition was obtained by transfer of the soft metal.