Nonvolatile semiconductor storage device capable of correctly reading selected memory cell and read method

Abstract

A selected memory cell is correctly read even when a threshold value of a non-selected memory cell that shares a word line is low. When reading a memory cell MC , a discharge transistor select circuit selectively discharges a bit line BL connected to the memory cell MC and two bit lines BL and BL that are adjacent to the bit line BL . A precharge control circuit fixes to a precharge voltage a center bit line among five bit lines that include a bit line BL connected to the memory cell MC and four bit lines that are adjacent to the bit line BL and brings the remaining bit lines into a floating state with the precharge voltage. Thus, the potential of the bit line BL is prevented from being lowered as a consequence of a leak current occurring via the non-selected memory cell MC when the threshold value of the selected memory cell MC is high, by which the erroneous determination that the ON-state is provided is prevented from being made.