A semiconductor device correctly switches endian modes regardless of the current endian mode of an interface. The semiconductor device includes a switching circuit and a first register. The switching circuit switches an interface tote used in big endian or little endian mode. The first register holds control data of the switching circuit. The switching circuit sets the interface in little endian mode when first predetermined control information is supplied to the first register, and sets the interface in big endian mode when second predetermined control information is supplied to the first register. The control information can be correctly inputted without being influenced by the endian setting status.