An authentication apparatus includes a data storage unit for storing authentication apparatus identification information, an interface unit for connecting to a host device through a first interface, and an authentication processor that executes an authentication process using the authentication apparatus identification information stored in the data storage unit. The authentication processor executes the authentication process upon receipt of an authentication request signal from the host device through the interface unit, and outputs an authentication response signal including data indicative of a result of the authentication process to the host device via the interface unit. The authentication request signal is for requesting authentication of a data storage device connected to the host device through a second interface.