High-frequency amplifier circuitry includes first amplifier circuitry, second amplifier circuitry, and noise figure improving circuitry. The first amplifier circuitry includes a first transistor and a grounded-gate third transistor. The first transistor has a source grounded via a first source inductor and a gate to which an input signal is applied. The third transistor is configured to output from a drain a signal obtained by amplifying a signal outputted from a drain of the first transistor. The second amplifier circuitry includes a same circuit constant as a circuit constant of the first amplifier circuitry and includes a second transistor and a grounded-gate fourth transistor. The noise figure improving circuitry connects the source of the first transistor and the source of the second transistor to each other.