To provide a semiconductor device provided with an element isolation structure capable of hindering an adverse effect on electric characteristics of a semiconductor element, and a method of manufacturing the same. The 1-chip microcomputer judges fault of sensor function when the sensor output signal is out of a specified output range. Monitoring of arcs is most advantageously effected on a fractal subset of low logarithmic order where the amplitude is higher pursuant to the 1f characteristic of electric arcs, where cross-induction among neighboring circuit is lower, and where travel between the arc and the arc signature pickup is longer than at the high frequencies customary for electric arc detection. This allows the holding arm to be pliable upwardly in case of emergency.