A semiconductor nonvolatile memory wherein a unit cell is constructed of a series connection consisting of an MNOS (metal--silicon nitride--silicon dioxide--semiconductor) transistor whose gate electrode is made of polycrystalline silicon and an MOS (metal--silicon dioxide--semiconductor) transistor whose gate electrode is also made of polycrystalline silicon, such unit cells being arrayed in the form of a matrix, and wherein the gate electrode of the MOS transistor is used as a reading word line, the gate electrode of the MNOS transistor is used as a writing word line, and a terminal of either of the MNOS transistor and the MOS transistor connected in series and constituting the unit cell is used as a data line.