1. A method for determining a plurality of wiring routes in an area by utilizing an artificial neural network, comprising the steps of: dividing said area into a plurality of smaller areas; representing each boundary among said plurality of smaller areas through which one of said plurality of wiring routes is capable of passing as an artificial neuron; changing an output value of an artificial neuron in accordance with whether or not a wiring route actually passes through a boundary which is represented as said artificial neuron; composing an artificial neural network in which interaction between artificial neurons is taken into consideration according to prescribed conditions restricting each of said plurality of wiring routes while changing output values of said artificial neurons, said prescribed conditions including: (1) for each of said wiring routes, at least one route must exist that passes through said boundary without being cut, (2) each of said wiring routes must not diverge or join a plurality of said wiring routes at an arbitrary boundary, and (3) a number of said wiring routes passing through a boundary must be less than a predetermined number; converging said output values of all of said artificial neurons of which said artificial neural network is composed; and determining each of said plurality of wiring routes by judging whether or not each of said plurality of wiring routes passes through a boundary represented as an artificial neuron according to said output values of said artificial neurons.