A ferroelectric-type nonvolatile semiconductor memory comprising:first and second memory units having bit lines, transistors for selection, sub-memory units composed of memory cells, and plate lines shared between the sub-memory units,wherein the first and second sub-memory units are formed on a same first insulating layer and another of the first and second sub-memory units are stacked over those units via a second insulating layer,each memory cell comprises a first electrode, a ferroelectric layer and a second electrode,in the first memory unit, a first common electrode is connected to the first bit line through one of said first transistors for selection, and the second electrode of each memory cell is individually connected to a shared plate line,in the second memory unit, a second common electrode is connected to the second bit line through one of said second transistors for selection, and the second electrode of each memory cell is individually connected to one of said shared plate lines,the first insulating layer memory cells have the same thermal history and have a thermal history different from the thermal history of the second insulating layer memory cells,a first reference potential, different from a second reference potential, is provided to the second bit line when data stored in the memory cells of the first memory unit is read out, anda second reference potential is provided to the first bit line when data stored in the memory cells of the second memory unit is read out.