A device and method is provided for commonly and securely allowing, as access control on a memory card, a plurality of information processing apparatuses to lock/unlock the memory. On the basis of a lock command input from an information processing apparatus serving as a host, such as a PC, an information storage device, such as a memory card, determines whether (a) a standard lock key set serving as a key set prohibiting output or (b) an export lock key set serving as a key set permitting output is detected and stores corresponding key set information. Only when the export lock key set is detected, output is permitted provided that predetermined verification succeeds.