PURPOSE: To obtain a sheet-shaped wire harness by adjacently aligning insulated coated electric wires into a sheet shape, coating molten thermoplastic copolymerized polyester and solidifying it, and binding the wires in package.

CONSTITUTION: Insulated coated electric wires 3aW3c with different diameters are adjacently aligned in the required order in grooves 9 of a jig 8 with the flat surface shape according to the objective to form an electric wire group 2. Molten thermoplastic copolymerized polyester is pressed to the electric wire group with the proper pressure and coated and allowed to bite into gaps, and a film 5 with the flat surface is formed and cooled and solidified. When an electric wire group 4 is to be branched from the electric wire group 2, molten thermoplastic copolymerized polyester is coated in the S-shaped coating profile to form a coating film 7, and the flat surface shape of the branch portion can be maintained. A product maintaining the preset flat surface shape as a wire harness can be easily obtained according to this constitution, and the installation to the equipment is facilitated.