An automatic trace determination apparatus comprises: first means that performs a first process sequentially for all intersections formed between tentative traces connecting between pads and corresponding vias, wherein the first process determines distances from an intersection formed between two tentative traces to the corresponding vias, respectively, and allows one of the two tentative traces associated with the longer distance to bypass the via, with which the other of the two tentative traces associated with the shorter distance is connected; and second means that performs a second process sequentially for all intersections formed between the interim traces themselves or between the interim and tentative traces, wherein the second process determines distances from an intersection to the vias corresponding to the interim or tentative traces, respectively, and allows one of the two tentative or interim traces associated with the longer distance to bypass the via, with which the other of the two tentative or interim traces associated with the shorter distance is connected, and defines this bypass trace as an optimal trace.