The method of driving a semiconductor device and a semiconductor device

An object of the present invention is to provide a semiconductor device having a new structure, the semiconductor device even when the power supply is not stored data can be held, and has an unlimited number of write cycles. The semiconductor device includes a memory cell which comprises, for example, wide-gap semiconductor, an oxide semiconductor, and the semiconductor device includes a voltage conversion circuit, the voltage converting circuit for outputting a potential lower than the reference potential for reading data from memory cells. By means of a wide-gap semiconductor, capable of providing reduced off-state current can be sufficiently contained in the memory cell transistor and the semiconductor device capable of holding data long.