A compound semiconductor device includes: a substrate; a first compound semiconductor layer formed over the substrate; a second compound semiconductor layer formed over the first compound semiconductor layer; and an upper electrode formed over the first compound semiconductor layer, wherein two-dimensional hole gas is generated in a region of the first compound semiconductor layer, the region being located at an interface between the first compound semiconductor layer and the second compound semiconductor layer, so as to have a hole concentration that decreases with increasing distance from the upper electrode.