In this paper, a laser displacement sensor Is combined with the strain gauge method for measuring the elastic deformation of a tool- workpiece Interface In cold forging. A 1-mm-diameter hole is bored radially to the depth of about 1.2 mm from the Inside surface of a die container and a steel pin Is placed in the hole for detecting radial displacements near the dle-workpiece interface. The coll spring pushes the detection pin Inward In the radial direction, while the radial displacement of the dle-workpiece Interface pushes It outward. The detection pin head faces the laser sensor head for optically measuring variations in the gap between the head of the detection pin and the laser sensor head. The displacement of the laser sensor Is simultaneously measured by the strain gauge method for adjusting the measurement obtained from the laser sensor. This combined technique Is applied to measure die deformation In the backward extrusion process of pure aluminium, and the displacement distribution over the dle-workpiece Interface with various tool dimensions Is obtained. In particular, we consider the Influence of the reduction In area and demonstrate that the proposed method Is useful for measuring die deformation in forging.