1. A method of repairing a memory device including a boot memory region, a normal memory region, and a redundant memory region, the redundant memory region including a plurality of repair memory units, the method comprising: repairing the boot memory region by performing at least one of excluding first fault memory units of the boot memory region from use as storage and replacing the first fault memory units with boot repair memory units of the repair memory units, each of the first fault memory units having at least one fault memory cell; and after the repairing the boot memory region is completed, repairing the normal memory region by performing at least one of excluding second fault memory units of the normal memory region from use as storage and replacing the second fault memory units with normal repair memory units of the repair memory units, each of the second fault memory units having at least one fault memory cell.