If the number of error bits of the data read from the memory cells of the third word line WL3 exceeds the reference number of error bits, the ECC circuit 122 may provide error bit information BE3 to the reclaim management unit 123. For example, the error bit information BE3 may include information about the number of error bits of the read data. The reclaim management unit 123 may perform the read reclaim operation on the third word line WL3. However, the present inventive concept is not limited thereto. For example, the reclaim management unit 123 may perform the read reclaim operation on the word lines WL3, WL4, and WL5 of the second zone Zone_2a. In this case, the read reclaim operation may be performed on the word lines WL3 to WL5 in the same zone of Zone_2a. In an exemplary embodiment, the reclaim management unit 123 may perform the read reclaim operation on all the word lines WL1 to WL8. In this case, the read reclaim operation may be performed on all the word lines WL1 to WL8 in the selected block BLKz.

As described with reference to FIGS. 5 and 6, if a read count associated with the third zone Zone_3a reaches the threshold value N3, the reliability verification read operation may be performed on word lines included in the third zone Zone_3a; if a read count associated with the fourth zone Zone_4a reaches the threshold value N4, the reliability verification read operation may be performed on word lines included in the fourth zone Zone_4a.