1. A similarity analyzing device comprising: an image acquisition section which acquires a plurality of picked-up images with which image pick-up dates and/or times are associated; an image registration section which registers a face image which shows a picked-up face and with which an image pick-up date and/or time is associated; a degree of similarity calculation section which detects a face of each of the plurality of picked-up images acquired by the image acquisition section and calculates the degree of similarity between the detected face and the face in the face image registered in the image registration section; and a degree of similarity reduction section in which the larger a difference between the image pick-up date and/or time associated with the picked-up image and the image pick-up date and/or time associated with the face image is, the more the degree of similarity of the face calculated by the degree of similarity calculation section is reduced.