A p-type well is formed in a semiconductor substrate, and an n+-type semiconductor region and a p+-type semiconductor region are formed in the p-type well to be spaced apart from each other. The n+-type semiconductor region is an emitter semiconductor region of a bipolar transistor, and the p-type well and the p+-type semiconductor region are base semiconductor regions of the bipolar transistor. An electrode is formed on an element isolation region between the n+-type semiconductor region and the p+-type semiconductor region, and at least apart of the electrode is buried in a trench which is formed in the element isolation region. The electrode is electrically connected to the n+-type semiconductor region.