1. A person recognition apparatus, comprising: an input device to input image data; a face detection device configured to: detect a face area in which a face of a person is expressed from the inputted image data, and to output a score with a large value when a face is detected, and a small value when a face is not detected, based on a brightness value of each pixel of the inputted image; detect and output a size of the face in a longitudinal direction and a lateral direction; detect and output a yaw direction, a pitch direction, and a roll direction of the face; a number of candidates calculation device configured to: adaptively determine a threshold value relating to a calculation of the number of candidates for each input, based on the value of the detected longitudinal direction, lateral direction, yaw direction, pitch direction, and roll direction of the face; display the facial images stored in the feature data administrative device in descending order of the similarity calculated by the person identification device; and calculate a number of facial images to be displayed in accordance with the threshold value, the score outputted from the face detection device, and the yaw direction, pitch direction, and roll direction outputted from the facial feature point detection device; and a candidate confirmation device configured to: display retrieval candidates of the facial images in descending order of the similarity and subject said facial images to visual inspection by a user, and recalculate the number of the facial images displayed by the number of candidates calculation device in accordance with an increase or decrease of the number of candidates to be confirmed.