This paper presents the progress of performance tests of ITER gyrotrons developed at QST and the design of dual-frequency (170 GHz and 104 GHz) gyrotrons to enhance various operation scenarios in ITER, such as characteristics studies of H-mode/ELM at low magnetic fields. The major achievements in developing the ITER gyrotrons are as follows: (i) manufacturing of eight ITER gyrotrons and their auxiliary components has been completed. Performance tests at QST have been progressing and four of the eight gyrotrons achieved the required test criteria—1 MW/300 s/50%, 5 kHz modulation with ⩾0.8 MW. Excitation of LP01 mode having a purity of ⩾95% was also successfully demonstrated using a 50 mm-diameter waveguide transmission line, satisfying the specification. (ii) The design of dual-frequency gyrotrons capable of 1 MW continuous-wave operation, was successfully completed.