As an analytical method to solve the mechanical behavior of jointed rock mass, a micromechanics-based continuum model of rock mass (MBC model) is proposed by H. Yoshida and H. Horii. The distinctive features of the MBC model are the followings: it can grasp the behaviors of joint; the informations on dominant joint sets such as strike and dip are employed as direct input data for the analysis; the opening and sliding displacement across joints are obtained as numerical results. To examine the performance of the proposed method, the excavation of the Okawachi power station cavern constructed by The Kansai Electric Power Co., Ltd. is analyzed and results are compared with measurement data in the present study.