A semiconductor device includes a first nonvolatile storage area including a plurality of sectors, a second nonvolatile storage area, a third nonvolatile storage area located in the first nonvolatile storage area, a fourth nonvolatile storage area located in the second nonvolatile storage area, and a control portion selecting one of a first mode and a second mode. In first mode, sectors where the third nonvolatile storage area is not located in the first nonvolatile storage area are used as a main storage area, and the second nonvolatile storage area is used to store a program or data that is read before the first nonvolatile storage area is accessed, the third nonvolatile storage area being used to store control information that controls writing, reading, and erasing of data involved in the first nonvolatile storage area or the second nonvolatile storage area. In the second mode, the first nonvolatile storage area is used as the main storage area, and the fourth nonvolatile storage area is used to store the control information.