A memory device according to the present invention includes multiple refresh modes and a refresh controller. A first refresh mode can respectively select one more memory block among a plurality of banks comprising a plurality of blocks and each of all banks. In addition, the first refresh mode may perform a refresh operation with respect to selected memory blocks. The second refresh mode can select a part of the banks and perform a refresh operation of data with a selected bank. The controller may select one of the first and second refresh modes in a refresh operation.