An image reading device includes a placement section, a reader, an authentication control section, and a reading control section. A document and an identification medium are placed on the placement section. The reader reads the document and the identification medium and generates image data. The authentication control section performs authentication of a user based on image data of the identification medium and generates authentication information that indicates a result of authentication of the user. The reading control section controls the reader. The reading control section controls the reader to read the document after generating the image data of the identification medium. The authentication control section starts authentication of the user after the image data of the identification medium is generated.