Abstract: A wire harness assembly work instruction device includes: a placement display for displaying an actual-size image of a wire harness in an overlapping manner; a product specification information storage unit for storing specifications of components, and a wiring order; a display unit for displaying the specifications of the components and the wiring order; a skill information storage unit for storing, for individual assembly workers, skill information; a production record storage unit for storing presence/absence of a production record of the wire harness; a worker information input unit for inputting information for identifying each worker; and a work instruction calculation unit for providing an instruction about the wiring order in accordance with skill information about each worker stored in the skill information storage unit.