According to example embodiments of inventive concepts: a semiconductor device includes: first and second trench gates extending long in one direction in a substrate; third and fourth trench gates in the substrate, the third and fourth trench gates connecting the first and second trench gates with each other; a first region defined in the substrate by the first to fourth trench gates and surrounded by the first to fourth trench gates; and a second region and a third region defined in the substrate. The second region is in surface contact with the first region. The third region is in point contact with the first region. The first region includes a first high-voltage semiconductor device including a body of a first conduction type and an emitter of a second conduction type in the body. Floating wells of the first conduction type are in the second region and the third region.