A method of operating a memory device includes determining a value of an operating current flowing through a selected first signal line, to which a selection voltage is applied, from among a plurality of first signal lines; dividing an array of memory cells into n blocks, n being an integer greater than 1, based on the value of the operating current; and applying inhibit voltages having different voltage levels corresponding to the n blocks to unselected ones of second signal lines included in the n blocks. Each of the unselected second signal lines is a pathway through which leakage current may potentially flow due to the operating current flowing through the selected first signal line and a memory cell addressed by the unselected second signal line and the selected first signal line.