1. A face detection method for detecting a face image contained in an inputted image, the method comprising the steps of: cutting out partial images having a predetermined size at different positions in the inputted image; calculating, for each of the partial images cut out at the different positions, an indicator value indicating a probability of the partial image being the face image; extracting all the partial images having the calculated indicator values not less than a first threshold value as candidates for the face image; setting each of the candidates as a candidate of interest, and when any nearby candidate, whose coordinate distance from the candidate of interest is not more than a predetermined distance, is present in the candidates other than the candidate of interest, setting the candidate of interest and the nearby candidate in one candidate group; calculating for each candidate group, based on the indicator values calculated for the candidates forming the candidate group, an integrated indicator value reflecting magnitudes of the indicator values; and extracting, as the face image, an image within a predetermined area in the inputted image containing the candidate group having the integrated indicator value not less than a second threshold value.