A memory device includes at least one memory, a controller controlling the at least one memory and a connect unit. The at least one memory includes a memory region comprising a plurality of memory cells, a redundant memory region comprising a plurality of memory cells and a redundancy information memory unit. The redundancy information memory unit stores redundancy information of the memory cells of the memory region. The controller includes a control unit. The control unit controls data read-out from the at least one memory and data to be written-in to the at least one memory according to the redundancy information stored in the redundancy information memory unit.