The authors classified discontinuous planes existing in rock mass for two types which are non oriented small cracks and the oriented joint sets presented by Yoshinaka et al. (1990). The total deformation of rock mass is assumed by superposing the elastic deformation of intact rock, the opening of non oriented small cracks, slip and the opening of oriented jont sets. The yield mode of the rock mass is selected that the the stress conditions is satisfy on yield surfaces at first in the three types as intact rock, cracks and joint sets. The excavated rock cavern and rock slope models are analyzed and the applicability of the presented method is examined.