Machine elements such as screws, gears, bearings, shafts, and springs are components needed for mechanisms. The performance improvement of machine elements is essential for that of the mechanical device. Therefore, in the machine design laboratory, we work toward the high performance and high strength of machine elements in terms of materials, machining, and surface treatments. Specifically, we are working on the performance evaluation of plastic gears using gear testing machines, the rolling contact fatigue life evaluation of bearings with a ball-on-disk contact tester, the sliding characteristic evaluation of steel using a high temperature tribometer.