An image reading apparatus having a security function that realizes highly precise authentication and high operability while suppressing an increase in manufacturing cost. An original 10 is placed on a platen glass 12, and an authentication card 80 is placed on a security information reading section 101. An image sensor 25 reads an image of the original 10 placed on the platen glass 12 and security information stored in the authentication card 80 placed on the security information reading section 101. A control section 4 controls processing of the image of the original 10 read by the image sensor 25 in accordance with the security information read by the image sensor 25.