Semiconductor memory is provided wherein a memory cell includes a capacitorless transistor having a floating body configured to store data as charge therein when power is applied to the cell. The cell further includes a nonvolatile memory comprising a resistance change element configured to store data stored in the floating body under any one of a plurality of predetermined conditions. A method of operating semiconductor memory to function as volatile memory, while having the ability to retain stored data when power is discontinued to the semiconductor memory is described.