A nitride semiconductor element 1 includes a base structure part 5, and an element structure part 11 formed on the base structure part 5 and having at least an n-type AlGaN based semiconductor layer 6, and p-type AlGaN based semiconductor layers 8, 9, 10, and further includes an n-electrode contact part 13a formed on the n-type AlGaN based semiconductor layer 6, an n-electrode pad part 13b formed on the n-electrode contact part 13a, and a p-electrode 12 formed on the p-type AlGaN based semiconductor layers 8, 9, 10, in which an AlN mole fraction in the n-type AlGaN based semiconductor layer 6 is 20% or more, the n-electrode contact part 13a includes one or more metal layers, and the p-electrode 12 and the n-electrode pad part 13b have a common laminated structure of two or more layers having an Au layer as an uppermost layer, and an Au diffusion preventing layer composed of conductive metal oxide and formed under the uppermost layer to prevent Au diffusion.