Nonvolatile memory device

A nonvolatile memory device comprises a page buffer unit comprising page buffers, each coupling first and second input and output (IO) lines and a latch circuit for outputting data together or coupling a sense node and the first or second I/O line together, in response to an operation mode; a Y decoder unit comprising decoders, each selecting one or more of the page buffers in response to address signals and outputting a first or second control signal to the selected page buffers in response to the operation mode; a mode selection unit outputting first and second operation selection signals for selecting the operation mode; and an I/O control unit comprising I/O control circuits, each detecting data, inputted and output through the first and second I/O lines, and outputting the detected data or coupling one of the first and second I/O lines to a data line.