A person retrieval apparatus (1, 2, 3) for retrieving registration information of a person using face image information, comprising: an extraction section (113, 213, 313) configured to extract the face image information from images taken by one or more cameras (111, 211, 311); a position storage section configured to store information indicating a priority level of person retrieval processing according to an image-taking position of each camera (111, 213, 313); a setting section (124, 224, 324) configured to set a reliability level to the face image information extracted by the extraction section (113, 213, 313) using the information indicating the priority level of the person retrieval processing according to the image-taking position of each camera (111, 213, 313) stored in the position storage section; a memory configured to store the face image information extracted by the extraction section (113, 213, 313) and the reliability level set by the setting section (124, 224, 324) in association with each other; and a retrieval section configured to perform the person retrieval processing on each piece of face image information stored in the memory, in descending order of the reliability level corresponding to each piece of face image information, wherein the reliability level is set in ascending order of a face detection number, the face detection number being a number of images in which a face is detected, wherein the setting section (124, 224, 324) is configured to set the reliability level in each piece of face image information, which has the highest priority level of the person retrieval processing on the image-taking position of a camera (111, 213, 313) having taken an image, which is an extraction source of each piece of face image information, so that the person retrieval processing is most-preferentially performed, wherein the position storage section is further configured to store position relation information indicating a position relation to the image-taking position of each camera (111, 213, 313), and wherein the setting section (124, 224, 324) is further configured to set the reliability level corresponding to the face image information extracted from images taken by each camera (111, 213, 313) so that the reliability level is relatively changed, using the position relation, which is indicated by the position relation information, between a camera (111, 213, 313) which has taken an image as the extraction source of each piece of face image information and other cameras (111, 213, 313). an extraction section (113, 213, 313) configured to extract the face image information from images taken by one or more cameras (111, 211, 311); a position storage section configured to store information indicating a priority level of person retrieval processing according to an image-taking position of each camera (111, 213, 313); a setting section (124, 224, 324) configured to set a reliability level to the face image information extracted by the extraction section (113, 213, 313) using the information indicating the priority level of the person retrieval processing according to the image-taking position of each camera (111, 213, 313) stored in the position storage section; a memory configured to store the face image information extracted by the extraction section (113, 213, 313) and the reliability level set by the setting section (124, 224, 324) in association with each other; and a retrieval section configured to perform the person retrieval processing on each piece of face image information stored in the memory, in descending order of the reliability level corresponding to each piece of face image information, wherein the reliability level is set in ascending order of a face detection number, the face detection number being a number of images in which a face is detected, wherein the setting section (124, 224, 324) is configured to set the reliability level in each piece of face image information, which has the highest priority level of the person retrieval processing on the image-taking position of a camera (111, 213, 313) having taken an image, which is an extraction source of each piece of face image information, so that the person retrieval processing is most-preferentially performed, wherein the position storage section is further configured to store position relation information indicating a position relation to the image-taking position of each camera (111, 213, 313), and wherein the setting section (124, 224, 324) is further configured to set the reliability level corresponding to the face image information extracted from images taken by each camera (111, 213, 313) so that the reliability level is relatively changed, using the position relation, which is indicated by the position relation information, between a camera (111, 213, 313) which has taken an image as the extraction source of each piece of face image information and other cameras (111, 213, 313).