To provide a card that excels in the data holding characteristic by refreshing the data stored in a flash memory when the card is connected again to a host after it is not connected to the host for a prescribed time or longer.

A flash ATA-PC card 1 is taken out of a host 2 and the power voltage supplied from the host 2 is stopped. Thus a power switch circuit 12 switches the power supply to a battery 14 to the power supply to a timer circuit 13, and the circuit 13 starts to count a prescribed time. Then the card 1 is connected again to the host 2, and the supply of power voltage is started again to the circuit 12 from the host 2. In such cases, the circuit 12 stops the supply of voltage to the circuit 13 from the battery 14. Then an MPU 6 of a flash disk control circuit 3 refreshes the data stored in a flash memory 4 in a prescribed procedure when the power voltage is supplied again from the host 2 and before every circuit contained in the card 1 is initialized.