1. A face detection apparatus for detecting a face contained in an input image comprising: a face detection section for detecting a face contained in the input image, based on a predetermined frame rate and face detection throughput per frame; an accuracy changing section for changing, when no face is detected by the face detection section, an accuracy in detecting a face by the face detection section by reducing the frame rate; and a storage section for storing, when a face is detected by the face detection section, as accuracy change history, the accuracy, which is changed by the accuracy changing section, in detecting a face by the face detection section, wherein when no face is detected by the face detection section, the accuracy changing section changes the accuracy in detecting a face by the face detection section based on the accuracy change history stored in the storage section.