Automatic trace determination apparatus comprises: means for setting candidate starting route and candidate ending routes that are tangent to an obstacle existing on a straight line connecting between a starting point and an end point of a trace; means for, when a plurality of obstacles exist on the straight line, setting, with respect to each pair of two of the obstacles, straight routes, each of which is tangent only to such two obstacles and does not intersect with any obstacle other than such two obstacles; means for setting tentative routes, each of which includes any one of the candidate starting routes and any one of the candidate ending routes and, when the plurality of obstacles exist, may further include any of candidate intermediate routes selected with respect to each pair of the obstacles; and means for, among the tentative routes, determining the tentative route that has the shortest distance between the starting point and the end point as an optimal trace route.