Knowledge of the mechanical properties of rocks at high pressure and temperature is fundamental not only for material science but also for earth science, such as for solving the mechanism of earthquakes and tectonic processes. For example, physical bases of the earthquake prediction based on the rock mechanics have been proposed, and extensive seismological, geophysical and geochemical observations have been conducted to find precursory phenomena before large earthquakes. However, we cannot help telling for the present that we do not have sufficient knowledge of an effective and reliable method for earthquake prediction. The book is mainly concerned with comprehensive source of information on the mechanical properties and behavior of rocks under high pressure that scans current state-of-the-art knowledge and shows contribution in establishing an experimental basis for the understanding of the mechanism of rock deformation in the earth's interior. The book can be used as textbook for graduate students by university teachers to prepare courses and seminars, and for active scientists and engineers who want to become familiar with a fascinating new field.