By development of a new triaxial compression technique, all components of principal stresses and strains of rocks were measured under general triaxial stress states in which the intermediate compression is not always equal to the minimum or maximum compression. The result shows that dilatancy is highly anisotropic under the general triaxial stress states. Previous experimental results on intact rocks and faulted rocks including the results reported in this paper suggest different rupture processes in the earth's crust which may be due to differences of the state of the earth's crust with respect to such factors as its mechanical structures, stress states, and so on. In some regions, marked precursors can be observed, but in other regions, it may be difficult to observe any appreciable precursors.