An image processor comprising: an image data acquirer configured to acquire a plurality of image data; a face image detector configured to detect face images from the plurality of image data acquired by the image data acquirer; a person identifier configured to perform same person determination processing based on the face images detected in the face image detector to classify the face images into image groups each including face images of a single person, thereby identifying persons corresponding to the respective image groups; a main person determiner configured to determine at least one person as a main person from among the persons identified by the person identifier; an important person determiner configured to determine at least one person highly related to the main person as an important person based on the main person determined in the main person determiner, from among persons except the main person as identified by the person identifier, a storage configured to store the plurality of image data; an image data manager configured to classify the plurality of image data stored in the storage to manage the plurality of image data as predetermined management image groups; and a monitor configured to display management images representing the predetermined management image groups, respectively, wherein the main person determiner determines, as the main person, a person whose number of detected face images is largest, wherein the important person determiner determines a person who is seen with the main person on a largest number of image data as the important person, from among persons except the main person as identified by the person identifier, and wherein the image data manager highlights the management images displayed on the monitor when image data including at least one of the main person and the important person exists in the predetermined management image groups. an image data acquirer configured to acquire a plurality of image data; a face image detector configured to detect face images from the plurality of image data acquired by the image data acquirer; a person identifier configured to perform same person determination processing based on the face images detected in the face image detector to classify the face images into image groups each including face images of a single person, thereby identifying persons corresponding to the respective image groups; a main person determiner configured to determine at least one person as a main person from among the persons identified by the person identifier; an important person determiner configured to determine at least one person highly related to the main person as an important person based on the main person determined in the main person determiner, from among persons except the main person as identified by the person identifier, a storage configured to store the plurality of image data; an image data manager configured to classify the plurality of image data stored in the storage to manage the plurality of image data as predetermined management image groups; and a monitor configured to display management images representing the predetermined management image groups, respectively, wherein the main person determiner determines, as the main person, a person whose number of detected face images is largest, wherein the important person determiner determines a person who is seen with the main person on a largest number of image data as the important person, from among persons except the main person as identified by the person identifier, and wherein the image data manager highlights the management images displayed on the monitor when image data including at least one of the main person and the important person exists in the predetermined management image groups.