This paper proposed an estimation method of JMA intensity using a multi-regression formula with acceleration response spectrum. The estimated JMA intensities from the multi-regression relationship agree well with observed values. Combination of the proposed method with the attenuation relation of acceleration response spectrum and the amplification factors of subsurface can predict the distribution of JMA intensities for large area. Furthermore, this estimation method was applied to the inversion of earthquake fault by using genetic algorithm. From numerical experiments, it is confirmed that the identified results show enough accuracy to predict an isoseismal map for large area.