Many researchers have investigated the friction factor of stepped channel flows, but general agreement has not been obtained. Because a method for evaluating a supercritical depth of the stepped channel flow might not be established. Further, the hydraulic condition required to form a quasi-uniform flow on the steppedchannel has not been clarified. This paper presents the flow resistance of skimming flows, which is characterized by the formation of the corner eddy for each step. In order to estimate the equilibrium condition of skimming flows, the subcritical depth of the jump immediately below the step channel end has been utilized. Two methods for evaluating a clear water depth of skimming flows have been developed for a wide range of channel slopes. Under a quasi-uniform flow, the friction factor of skimming flows has been clarified systematically.