A storage medium can be mounted at and dismounted from an information processing apparatus without having to dismount a storage medium adapter from the information processing apparatus, and one of the storage medium and the storage medium adapter can be selectively ejected, while providing an improvement of operating performance and the like. When the storage medium is ejected from the storage medium adapter, a first conveying roller rotates 90° counterclockwise by the forward rotation of a driving motor, and due to an arc portion contacting the storage medium, the storage medium is ejected by the first conveying roller and a first driven roller. When the storage medium adapter is ejected from a socket, a second conveying roller rotates 180° counterclockwise by the backward rotation of the driving motor, and due to an arc portion contacting the storage medium, the storage medium adapter is ejected by the second conveying roller and a second driven roller.