A harness verification method includes placing a three-dimensional model in virtual space and displaying a model plane onto which an overhead view of the three-dimensional model is projected, setting reference planes in the virtual space and displaying on the display cross-section projection planes onto which cross sections defined by intersection of the three-dimensional model and the reference planes is projected; obtaining a pointing position operated by a pointing unit in the virtual space, designating the pointing position as an operation position, identifying the operation position as a pass point of a harness, generating curve segments each corresponding to section between two adjacent pass points, and storing in the storage unit definition information that defines a route of the harness on the basis of jointed curve segments; and displaying on the cross-section projection planes the route of the harness generated on the cross section on the basis of the definition information.