To reduce the power consumption of a memory card by measuring the continuous time of a standby mode in a memory part and switching the mode to a sleep mode when the measured value exceeds a prescribed value.

The memory card 1 is provided with an input/output interface circuit part 2 satisfying the standard of PCMCIA and a memory part 3 constituted of an IC memory having an active mode, the standby mode and the sleep mode whose consumption current becomes lower than the standby mode. The input/output interface circuit part 2 and the memory part 3 are connected by an internal bus 4 composed of plural signal lines. An information processing unit 5 identifies the operation modes of the memory part 3, measures continuous time being the standby mode and gives a command so that the operation mode is switched to the sleep mode to the memory part 3 when measured time exceeds the prescribed value.