The present invention is directed to improve reliably of an on-chip redundancy system by preventing influence of a physical failure exerted on an entire semiconductor chip. A comparator measure for comparing outputs of an on-chip redundancy system is mounted on a semiconductor chip different from the on-chip redundancy system. The another semiconductor chip is, preferably, mounted on a semiconductor chip on which a power source circuit for supplying power to the on-chip redundancy system redundantly having the comparing function in the chip, a driver circuit for driving an output circuit, and the like are mounted. With the configuration, the influence of a failure occurring in the on-chip redundancy system can be prevented from being exerted on the comparator measure.