This paper proposes a method for the evaluation of seismic wave, considering more effective representation of destructiveness of seismic wave. Specifically, a seismic wave energy spectrum is newly defined by decomposing the seismic wave energy into the frequency domain, and a ground motion attenuation law for the seismic wave energy spectrum is proposed. The wave form through this representation, which is considered as the best one for design and assessment of structures can be established along with the temporal characteristics which are beyond the scope of this study. The proposed attenuation law is considered to be utilized for a probabilistic seismic hazard analysis in which one aspect of the seismic ground motion such as PGA or PGV has been focused so far.