Provided is a power feeding structure for a sliding door, in which the wire harness is routed from a swinging member placed near a rear portion of a vehicle body-side step portion to a sliding door-side swinging member through an opening behind the step portion, and a forward turning angle of the vehicle body-side swinging member is restricted so that the wire harness forms a projection which projects from the vehicle body-side swinging member toward an outer side of the vehicle than the step portion and a curved portion which projects in a convex form outward of the vehicle when the sliding door is slid forward of a vehicle and is fully closed. When the sliding door is fully closed, the sliding door-side swinging member is biased inward of the vehicle by a spring member.