We discuss millimeter-wave film bulk acoustic resonator (FBAR) with very thin aluminium nitride (AlN) film fabricated using metal organic chemical vapor deposition (MOCVD) method. In previous works, we have successfully grown c-axis oriented AlN film using MOCVD method on Ru/Ta/SiO2/Si substrate. In this paper, we grew excellent orientation films of AlN and Ru electrodes in MOCVD, although their film thickness were very thin. Experimental results show that full width at half maximum (FWHM) is 1.3° at AlN thickness of 30 nm. In calculating analysis, when both top and bottom electrode thicknesses were 20 nm and AlN thickness was 30 nm, we obtained that resonant frequency was higher than 50 GHz. Therefore, FBAR is possible to apply to millimeter-wave bands devices, also contribute to small-size, low power consumption and low cost for millimeter-wave terminals.