A nonvolatile memory device including a memory cell array, a first voltage generator configured to generate a word line operating voltage for each word line of the memory cell array, a second voltage generator configured to generate a bit line operating voltage of the memory cell array, and a temperature unit configured to determine, from a temperature range table, a temperature range for a temperature code according to a real-time temperature of the memory cell array, and to adjust a power supply voltage of the first or second voltage generator based on a selection signal mapped to the determined temperature range.