A memory device includes memory cells connected to a first word-line, wherein the memory cells include a data region in which data is stored and a counting value backup region in which the number of times the first word-line is activated is backed up, a counting table for storing a first row address corresponding to the first word-line and a first counting value as a counting result of the number of times the first word-line is activated, and a comparator configured to compare the first counting value with a first backed-up counting value stored in the counting value backup region; and when the first counting value is greater than the first backed-up counting value, back up the first counting value in the counting value backup region, or when the first backed-up counting value is greater than the first counting value, overwrite the first backed-up counting value into the counting table.