An authentification device includes: an acquisition unit configured to acquire and detect a voice signal of an utterance voice of a speaker; an authentication unit configured to authenticate whether the speaker is the person himself/herself based on collation between the voice signal detected by the acquisition unit and a database; a storage unit configured to store, as question example sentences, a plurality of questions for acquiring a voice signal used for authentication of the speaker by the authentication unit; a display interface configured to display the question example sentence for the speaker on a terminal device; and an example sentence selection unit configured to select a question example sentence to be displayed on the terminal device from the plurality of question example sentences stored in the storage unit.