A nonvolatile memory device includes a sense amplifier circuit sensing first data from a memory cell via a bit line and outputting the sensed first data, in response to a read command. A write driver circuit programs the memory cell and stores second data indicating a programming state of the memory cell, in response to a program command. A verification block outputs a result of a comparison between the first and second data in response to a first read command. The second data is updated based on the determination on the programming of the memory cell in response to a second read command applied following the first read command.