This paper presents the effect of surface soil in the horizontal force distributions in earthquake responses along the height of mid-rise reinforced concrete buildings. It is dealt with a lot of surface soil models and artificial earthquake waves to input into these models. Surface waves filtered through surface soil are calculated. Then, we input those surface waves to the reinforced concrete buildings to obtain earthquake responses. Consequently, we investigate the horizontal force distributions in the earthquake responses of the buildings and propose an evaluation method of these distributions.