A semiconductor integrated circuit includes a level shifter formed in a portion of a high-voltage junction termination structure and an isolation region formed surrounding the periphery of the level shifter. The level shifter includes a p-type base region formed in an upper portion of a p− substrate, an n− source region formed contacting the base region, an n+ drift region formed contacting the base region, a drain region formed in an upper portion of the drift region, and a control electrode that controls the voltage of the base region. In a planar pattern, an effective channel width defined by the width of the base region in a portion that overlaps with the control electrode is greater than the width of the drain region as measured along the same direction as the effective channel width.