A semiconductor device has a first semiconductor region of a first conductivity type, a second semiconductor region of a second conductivity type, a first conductive layer disposed on a main surface of the first semiconductor region, and a second conductive layer disposed on a main surface of the second semiconductor region. The first conductive layer has a first diffusion layer of the first conductivity type, a plurality of second diffusion layers of the first conductivity type, the second diffusion layers having higher impurity concentration than the first diffusion layer, and a plurality of third diffusion layers of the first conductivity type that are included in the first semiconductor region, or are arranged apart from one another to contact the first and second semiconductor regions, the third diffusion layers being arranged apart from the plurality of second diffusion layers and having higher impurity concentration than the first diffusion layer.