A semiconductor device according to the present invention includes: a substrate; a plurality of trenches formed in the substrate; and a plurality of functional element forming regions arrayed along each of the trenches, including a channel forming region as a current path, wherein the plurality of functional element forming regions includes a first functional element forming region in which the area of the channel forming region per unit area is relatively small and a second functional element forming region in which the area of the channel forming region per unit area is relatively large, and the first functional element forming region is provided at a region where heat generation should be suppressed.