1. A portable information terminal device comprising: an imaging unit for photographing an object; imaging unit starting means for executing an initialization process of said imaging unit by supplying a power source to said imaging unit on the basis of operation by a user; photographing control means for controlling photographing operation performed by said imaging unit; characteristic information storage means for storing characteristic information extracted from face images as registered characteristic information in advance; and authentication processing means for performing an authentication process by using said registered characteristic information on the basis of an image photographed by said imaging unit, wherein said photographing control means starts photographing on the basis of completion of said initialization process of said imaging unit by said imaging unit starting means.