Abstract An analysis method that can grasp the behavior of a rock mass is necessary to establish a rational method for designing and constructing large-scale caverns. In underground excavation, sliding and opening of joints due to stress relaxation are considered to be the governing mechanisms of the behavior of a jointed rock mass. In the present study, a micromechanics-based continuum model of a jointed rock mass is proposed and an analysis method for underground excavation is developed. To examine the performance of the proposed method, the excavation of Shiobara power station cavern constructed by the Tokyo Electric Power Co., Ltd. is analyzed and results are compared to measured data. In numerical results, for instance, displacement of the measurement facilities during excavation are in good agreement with measured data.