An object is to provide a semiconductor device with a novel structure, which can hold stored data even when not powered and which has an unlimited number of write cycles. A semiconductor device includes a memory cell including a widegap semiconductor, for example, an oxide semiconductor and the semiconductor device includes a potential conversion circuit which functions to output a potential lower than a reference potential for reading data from the memory cell. With the use of a widegap semiconductor, a semiconductor device capable of sufficiently reducing the off-state current of a transistor included in a memory cell and capable of holding data for a long time can be provided.