Mechanical properties of potato and sweet potato were measured under impact and compression loading. The test apparatus consisted of disgital storage oscilloscope and simple mechanisms which can apply compression and impact forces to potatoes and sweet potatoes. The mechanical properties could be measured while the tissues were ruptured in a very short period time less than 10 ms by impact loading. Rupture force, energy, and deformation were measured as mechanical properties of potatoes and sweet potatoes under impact and compression loading. Rupture forces under impact and compression loading were in the range of 84.1 to 93.7N and 128.9 to 132.2N for external tissues and 60.1 to 64.8N and 158.9 to 171.1N for internal tissues of potato and sweet potato, respectively. Compression speeds and drop heights for each test were in the range of 1.25 to 62.5mm/min and 8 to 24cm.