The new method of non-contact measurement of linear displacement described in this paper utilises the large changes in the field of a permanent magnet with distance. The output of a magnetic field detector is fed to a microprocessor programmed to display the distance between the magnet and the detector directly. The maximum measurable displacement is limited by the size of the permanent magnet and the noise level of the detector. In the present version of the instrument, the accuracy is better than 2.0% of full-scale deflection (FSD) over the entire useful range of 250 mm and better than 0.1% FSD for displacements less than 110 mm.