A magnetic indexer for locating a device producing a magnetic field in a blind or inaccessible position of a work piece. A magnet is initially placed on a first side of the work piece such that a magnetic field produced by the magnet extends through the work piece and substantially perpendicular to a surface of the work piece. A device comprising a plurality of probes for sensing magnetic fields is then positioned over a second surface of the work piece. The probes are then moved over the second surface to determine the location of the axis of the magnet via the strength of the sensed magnetic field. Once the position of the axis of the magnet is determined, the work surface is either marked or worked on through the platform on which the probes are positioned. In particular, a hole may be accurately drilled or otherwise formed directly over the magnet even when the first surface of the work piece cannot be seen. Additionally, the present invention allows a very accurate positioning of a work tool on the second surface without the need to first visualize the first surface of the work piece.