Provided is an iris authenticating device allowing cost to be easily reduced.An iris authenticating device includes: a photographing element 2 obtaining an optical image formed in a light-receiving surface 21 a lens unit 3 for forming an optical image of a photographed subject on the light-receiving surface 21 a driving mechanism 4 moving the lens unit 3 in a light axial direction an image capturing unit 51 capturing a plurality of images obtained by the photographing element 2 corresponding to a plurality of focusing positions associated with position variation of lens accompanied with movement of the lens unit 3 a contrast detector 52 detecting contrast with respect to the plurality of images respectively an image selecting unit 53 selecting an image having the maximum contrast among the plurality of images and an authentication processing unit 54 performing iris authentication based on the selected image selected by the image selecting unit 53.本發明係提供容易減低成本之虹膜認證裝置。虹膜認證裝置係具備:攝影元件2,係取得形成於受光面21的光學影像;透鏡單元3,係用以將拍攝體的光學影像成像於受光面21;驅動機構4,係使透鏡單元3沿著光軸方向移動;影像取得部51,係取得與因應於伴隨著透鏡單元3的移動之透鏡的位置變化對應之複數個合焦位置而藉由攝影元件2所取得之複數個影像;對比度檢測部52,係對該複數個影像,分別檢測其對比度;影像選擇部53,係選擇該複數個影像之中之對比度最大的影像;以及認證處理部54,係根據藉由影像選擇部53所選擇的選擇影像而執行虹膜認證。1‧‧‧虹膜認證裝置2‧‧‧攝影元件3‧‧‧透鏡單元4‧‧‧驅動機構12‧‧‧底板21‧‧‧受光面31‧‧‧光軸32‧‧‧連結突起41‧‧‧旋轉體42‧‧‧手臂43‧‧‧導引構件411‧‧‧旋轉軸412‧‧‧突起部421‧‧‧搖動軸422‧‧‧狹縫423‧‧‧長孔B‧‧‧來回範圍
