We conducted a study to estimate damage to buildings considering the directional property of seismic ground motions and buildings. We created the fragility curve based on the ‘average direction’, which response is the average value in various directions. We found responses in the average direction and responses in the ‘maximum direction’, which response is the maximum in various directions have a strong linear relationship. We can estimate damage to buildings by the fragility curve based on the ‘average direction’ by using the response estimated from the response in the ‘maximum direction’, that can be calculated faster than the ‘average direction’.