A memory card has a plurality of non-volatile memories and a main controller for controlling the operation of the non-volatile memories. The main controller performs an access control to the non-volatile memories in response to an external access instruction, and an alternate control for alternating an access error-related storage area of the non-volatile memory with other storage area. In the access control, the speeding up of the data transfer between flash memories is achieved by causing the plurality of non-volatile memories to parallel access operate. In the alternation control, the storage areas is made alternative for each non-volatile memory in which an access error occurs.