A method for determining a wiring risk is a method for determining a first risk that electric wires connected to a plurality of terminal devices are bundled into a single harness, and a second risk that harnesses fail at the same time, wherein the first risk is determined by identifying the number of connectors to which a target harness identified from the plurality of harnesses is indirectly connected, and the second risk is determined by matching location information of the target harness to an influenced area by a hazard source, and identifying whether the target harness passes through the influenced area.