A high-frequency amplifier includes: a first transistor having a source connected to ground; a second transistor forming a cascode circuit with the first transistor; a series circuit connected between a gate of the second transistor and the ground, the series circuit being formed by a first resistive element and a series resonant circuit connected in series with each other; and a second resistive element connected in parallel to the series circuit. The high-frequency amplifier can achieve low distortion characteristics while ensuring operational stability in a wide band.