A server analyzes feature information including a whole body and a face of a person reflected in a video image sent from a monitoring camera and store a whole body image obtained by cutting out the whole body of the person and a face image obtained by cutting out the face of the person. In response to designation of a person of interest, the server executes first collation processing targeted for the whole body image of the person of interest and second collation processing targeted for the face image of the person of interest. Also, in response to identification of a person matching at least one of the whole body image and the face image of the person of interest by at least one of the first collation processing and the second collation processing, the server outputs a notification that the person of interest is found.