In this letter, a Ka-band cavity resonator using micromachining process is presented. A two-port cavity resonator is designed using the three-dimensional (3-D) design software, HP HFSS. The cavity resonator is fabricated on a Si substrate and bonded with a Quartz wafer. The resonator shows the resonant frequency of 39 GHz, the insertion loss of 4.6 dB, and the loaded quality factor (Q L ) and unloaded quality factor (Q U ) of 44.3 and 107, respectively.