A film bulk acoustic wave resonator of the invention includes a substrate; a resonant structure provided on the substrate constituted by a lower electrode, a piezoelectric film and an upper electrode; and an acoustic multilayer of a plurality of reflective films provided between the substrate and the resonant structure. At least one of the reflective films of the acoustic multilayer has a specified crystal plane orientation, and an X-ray rocking curve full width at half maximum that is preferably not greater than 10 degrees, and more preferably is not greater than 3 degrees. This makes it possible to obtain better resonance characteristics than in the case of the prior art, by increasing the efficiency with which bulk waves propagating towards the substrate are reflected.