Soft-error resistance and latch up resistance are simultaneously improved for LSI involving miniaturization and reducing operating voltage. P wells and N wells are formed in a higher density substrate (P on P+ substrate), and buried N wells are formed on a layer underlying thereof. A PMOSFET is formed in the N well and a NMOSFET is formed in the P well. A P well electric potential junction for coupling P well electric potential of the P well to predetermined electric potential is provided, and a region directly under the P well electric potential junction is provided with a region where the aforementioned buried N well is not disposed. The soft-error resistance is improved by having the buried N well therein, and the latch up resistance is improved by coupling the P well to the substrate.