The present invention provides a semiconductor device for accomplishing a high withstand voltage and improving dependability, and a method of manufacturing the semiconductor device without requiring an additional diffusion process at a high temperature and for long hours. A semiconductor device 1 includes a first semiconductor region 2B and a second semiconductor region 5 provided on a main surface of a substrate 2, being apart from each other and having first conductivity; a third semiconductor region 4 provided between the first semiconductor region 2B and the second semiconductor region 5 and having second conductivity opposite to the first conductivity; a fourth semiconductor region 41 provided on a main surface of the substrate 2, connected to the third semiconductor region 4, manufactured together with the third semiconductor region 4 in the same manufacturing process, and having the conductivity same as that of the third semiconductor region 4; and trenches 42 made on the main surface of the fourth semiconductor region 41 and having a depth smaller than a junction depth of the fourth semiconductor region 41.