A memory device controlling apparatus of the present invention includes a device information requesting part that requests device information with respect to a memory device, when recognizing that the memory device is connected to the memory device controlling apparatus, and an extension activating part that activates an extension of the memory device based on the device information acquired in the device information requesting part. The memory device controlling apparatus accesses the memory device using the extension in the memory device. Such a configuration enables the memory device and the memory device controlling apparatus to be operated in an optimum operation mode in accordance with the characteristics of each bus, a host PC, and the memory device.