PURPOSE: To obtain a planar type thyristor having small chip size and high forward and reverse withstand voltages by forming newly a field limiting ring only in the vicinity of the surface of a junction for holding the forward withstand voltage.

CONSTITUTION: An n type layer 22 is epitaxially grown on a p type Si substrate 21 becoming an emiter layer, and the layer 22 is insularly isolated via p type regions 25 reaching the substrate 21 formed at both ends. Then, a p type base region 23 is diffused in the layer 22 becoming insular, an n type emitter region is formed therein, and an n+ channel stop is formed in the layer 22 disposed outside of the region 23 to form a planar type thyristor. In this structure, a p type field limiting ring 27 deeper than the stop 28 is diffused in the layer 22 between the region 23 and the stop 28, and the forward and reverse withstand voltages are largely increased as compared with that having no such voltages.