A power amplifier includes: an input matching circuit including an inductor, the input matching circuit receiving an input signal and matching input impedances with each other; an amplifier amplifying the input signal that is passed through the input matching circuit; and a test circuit, wherein the test circuit includes: a capacitor connected to the inductor in the input matching circuit through first test switch; a negative resistance transistor provided between the inductor and first voltage source terminal with second test switch being interposed between the inductor and the negative resistance transistor; and a current source transistor provided between second voltage source terminal and the inductor, wherein, in testing, first and second test switches and the current source transistor are turned on to cause the inductor and the test circuit to form a oscillator and, in normal operation, first and second test switches and the current source transistor are turned off.