1. A face detection apparatus, comprising: a rectangle integral image (RII) unit for providing a rectangle integral image according to an original image; a feature mapping unit for determining a face candidate region according to a plurality of rectangular face feature templates, and calculating a plurality of feature values of the rectangular face feature templates according to the rectangle integral image; and a cascade and score unit for judging whether the face candidate region conforms to a plurality of cascade conditions, and giving the face candidate region a score according to the feature values when the face candidate region conforms to the cascade conditions, wherein the face candidate region is a non-face region if the score of the face candidate region is lower than a threshold value.