1. A failure detecting apparatus that detects failure of an imaging device comprising: acquiring means for acquiring a plurality of images captured by a plurality of imaging devices in which exposures thereof are capable of being individually controlled, the plurality of images including an overlapped region that represents a region where images are overlapped; region extracting means for extracting a plurality of overlapped regions from the plurality of images acquired by the acquiring means; feature extracting means for extracting features of image from the plurality of overlapped regions extracted by the region extracting means; comparing means for comparing the features of image between the plurality of overlapped regions; similarity determining means for determining whether or not the features of image are similar based on a result of comparing by the comparing means; and failure determining means for determining a failure in the imaging device when the similarity determining means determines the features of image are not similar.