Abstract: An electrical wiring harness structure constituting a multiplex transmission network in a vehicle, in which a vehicle body is divided into a plurality of blocks, electrical components are mounted in units of blocks to constitute modules, and thereafter, the modules are combined to complete a vehicle body. The structure includes control nodes, arranged in units of modules, for controlling communications of the electrical components mounted on the corresponding modules, wiring harnesses, arranged between the adjacent modules, for forming a transmission path for performing communications among the control nodes, and connectors for connecting the wiring harnesses and the control nodes.