An acoustic resonator includes: a substrate; a resonance part mounted on the substrate and including resonance part electrodes, the resonance part being configured to generate acoustic waves; a cavity disposed between the resonance part and the substrate; a frame part disposed on at least one electrode among the resonance part electrodes, and being configured to reflect the acoustic waves; and a connection electrode configured to connect the at least one electrode to an external electrode, and having a thickness less than a thickness of the at least one electrode.