A multi-asperity micromechanical model along with an energy approach is utilized to investigate the details of reflection, transmission and conversion of plane seismic waves incident upon a rough rock joint. In the multi-asperity micromechanical methodology, the behavior of a rock joint is obtained by considering the behavior of asperity contacts and the statistical description of rock joint surface topography. The overall average energy transmission through rock joint is obtained as the sum of the asperity contact average energy transmissions. The transmitted and reflected wave amplitudes obtained by this approach are found to be dependent upon the incident wave frequency, rock joint roughness, rock material properties and existing normal stress conditions.