In a semiconductor memory for reading and writing of stored charge in an X-Y address system by arranging a plurality of memory cells each including a capacitance element and one MOS-FET in matrix, this invention discloses a semiconductor memory using multiple level storage structure for read and write of at least more than two multi-level data stored in the capacitance elements, by applying a multi-level step voltage to the plate electrode of the capacitance or to the gate electrode of MOS-FET so as to write and read signal charge.