A semiconductor device 100 includes an element-forming region having gate electrode 108 formed therein, and a circumferential region formed in the outer circumference of the element-forming region and having an element-isolating region 118 formed therein. On the main surface of the semiconductor substrate 101, there is formed a parallel pn layer having an N-type drift region 104 and P-type column regions 106 alternately arranged therein. In the circumferential region, there is formed a field electrode 120, but the field electrode 120 is not formed on the P-type column regions 106. The P-type column regions 106 in the circumferential region are formed with a depth larger than or equal to that of the P-type column regions 106 in the element-forming region.