In a semiconductor device having a junction type diode using a bipolar transistor and a process for producing the same, a ratio of a diode electric current to a leakage electric current is improved, and latch up resistance is improved without increasing the process. A p type semiconductor substrate, a collector buried region and an n type epitaxial layer are formed, a p type first impurity region is formed in the n type epitaxial layer, an n type second impurity region is formed in the first impurity region, an N+ sinker is formed, and a collector electrode is formed, with a common electrode being formed on the first and second impurity regions.