Abstract: A card type peripheral apparatus is disclosed which can be removably inserted not only into a slot of an electronic apparatus of a small size but also into a slot of an external apparatus readily and with certainty. The apparatus includes a first case, an electronic part accommodated in the first case, and a connector provided at a first end in the lengthwise direction of the first case for electrically connecting an external apparatus to the electronic part. The attachment includes a second case. Mounting portions are provided at a second end in the lengthwise direction of the first case and a first end in the lengthwise direction of the second case such that the first and second cases are removably attached to each other at the mounting portions thereof while the lengthwise directions thereof are juxtaposed with each other.