An IC card is prevented from falling off readily an electronic device while maintaining the mechanical strength of the IC card. A recess for preventing a memory card from falling off an electronic device is provided at the side of one side of a principal surface of a cap of the memory card which is configured by fitting a memory body in a recess formed on a parts mounting surface of the cap. The bottom of the recess is terminated in the middle of the thickness of the cap. This construction makes it possible to prevent the memory card from falling off readily an electronic device while maintaining the mechanical strength of the memory card.