1. A face detecting method, for detecting faces while varying the inclination of faces to be detected in each frame of video images or each of a plurality of continuous images, which are input images, comprising: an information obtaining step, for obtaining information regard whether the input images are those obtained by continuous imaging or those obtained by video imaging; and an order setting step, for determining relative values of the probabilities that faces of predetermined inclinations will appear in each frame of video images or each image of the plurality of continuous images based on the obtained information, and setting the order of inclinations of faces to be detected according to an order corresponding to the relative values of the probabilities, wherein, in the case that the obtained information indicates that the input images are those obtained by continuous imaging, in the order setting step, the relative value of the probability that an inclination of a face same as an inclination of a face detected in an immediately preceding image appears in a continuous image which is a target of face detection is determined to be the highest, the inclination determined to have the highest relative value of the probability is set as the highest ordered inclination in the continuous image which is a target of face detection, and priorities for other inclination are set in the order that they are similar to the highest ordered inclination, and wherein, in the case that the obtained information indicates that the input images are those obtained by video imaging, in the order setting step, the relative value of the probability that an inclination of a face same as an inclination of a frame which is a target of face detection appears in the frame which is a target of a face detection is determined to be the highest, the inclination determined to have the highest relative value of the probability is set as the highest ordered inclination in the frame which is a target of a face detection, and priorities for other inclinations are set in the order that they are similar to the highest ordered inclination.