A card-type peripheral device includes an electronic component disposed in a case, and a terminal part including connection terminals connectable with a to-be-connected device, wherein a function of the electronic component and the number of terminals of the terminal part are maintained to be compatible with those of the to-be-connected device, and the outside dimensions of the case are set to be smaller than the outside dimensions of the to-be-connected device and greater than the outside dimensions of a predetermined small-size card.