A wire harness distributing method in which a wire harness is easily distributed with the aid of a trimming plate which is mounted to a wall surface such as a vehicle body panel, and once the trimming plate is mounted, even if the trimming plate is removed, all or part of the wire harness remains on the wall surface for easy maintenance. The method of distributing a wire harness with connectors to a wall surface such as a vehicle body panel includes the steps of: providing a first preliminary locking member for a wire harness on a trimming plate which is to be mounted to a wall surface; providing a second preliminary locking member to the wire harness, and detachably and preliminarily locking the wire harness to the trimming plate; and fixing the trimming plate and the wire harness to the wall surface.