A wire harness consists of electrical wires, a first resin sheet and a second resin sheet. The first resin sheet includes a recess formed so as to extend along a predetermined "three-dimensional" wiring route of the electrical wires. In order to manufacture the wire harness, at first, the recess is formed in the first resin sheet. Then, the electrical wires are arranged in the recess. Next, the second resin sheet is arranged on the first resin sheet so as to cover the recess and air contained in a space defined between the first resin sheet and the second resin sheet is sucked to the outside. Finally, the first resin sheet and the second resin sheet are joined to each other. Owing to the provision of the three-dimensional recess, it is possible to realize the wire harness having a three-dimensional configuration following to the actual wiring route of the electrical wires, so that the assembling property can be improved.