A nonvolatile memory device comprises a cell array connected to a plurality of bit lines in an all bit line structure, a page buffer circuit connected to the plurality of bit lines, and control logic configured to control the page buffer circuit. The control logic controls the page buffer circuit to sense memory cells corresponding to both even-numbered and odd-numbered columns of a selected page in a first read mode and to sense memory cells corresponding to one of the even-numbered and odd-numbered columns of the selected page in a second read mode. A sensing operation is performed at least twice in the first read mode and once in the second read mode.