In this paper, we propose an automatic detection method of the areas damaged by an earthquake. We use aerial images that are taken before and after the earthquake. To detect the damaged areas, we register these two aerial images. It is difficult to register two aerial images by using only the image information, and hence, we use digital map for registering them. First each aerial image is registered to the digital map by using the perspective transformation. Then we detect damaged areas by computing the differences between the registered images. The damaged areas can be detected automatically and correctly by our method.