The transistor includes an underlying layer 301 formed on a substrate 300, and a first layer (including an operation layer 302) made of a nitride semiconductor formed on the underlying layer 301. The underlying layer 301 is a multilayered structure including a plurality of stacked nitride semiconductor layers. The underlying layer 301 includes a transition-metal-containing layer containing at least one of cobalt, nickel, ruthenium, osmium, rhodium, or iridium which is a transition metal.