In a curve section, a comb tooth mark 28 is provided concentrically with a center line 44 of a running rail 4. A comb tooth sensor 34 on an overhead running vehicle 2 reads comb teeth 40. Then, corrections are made using the ratio of the radius of curvature (R) of the center line 44 and the radius of curvature (r) of the comb tooth mark 28. An encoder interpolates the areas between the teeth 40. Then, the position of the overhead running vehicle 2 in the curve section is determined. The present invention thus enables the exact position of the overhead running vehicle 2 to be recognized even when the overhead running vehicle 2 is located in a curve section. This makes it possible to provide a load port in a curve section.