A storage device may include a memory device and a memory controller. The memory device may include a memory block including a plurality of pages. When a sudden power off is detected in which power supplied to the memory device is abnormally interrupted during a normal program operation on one page among the plurality of pages, the memory controller may control the memory device to perform a dummy program operation on a selected page among the plurality of pages after the sudden power-off. The memory controller may control the memory device to perform the normal program operation and the dummy program operation by using an Incremental Step Pulse Program (ISPP) method. The memory controller may control the memory device to perform the dummy program operation in a smaller number of program loops as compared with the normal program operation.