An acoustic resonator includes: an upper electrode including a first active region disposed on an upper portion of a piezoelectric layer, and a first extended region extended from the first active region; a lower electrode including a second active region disposed on a lower portion of the piezoelectric layer, and a second extended region extended from the second active region; a first metal layer including a first resistance reduction region disposed on the first extended region; and a second metal layer including a second resistance reduction region disposed on the second extended region. The first metal layer includes a first conductive link region extended from the first resistance reduction region. The second metal layer includes a second conductive link region extended from the second resistance reduction region. The first and second conductive link regions correspond to respective portions of a side boundary of the first and second active regions.