An ultrasonic atomizing unit is provided which can spray fine particles of a liquid farther without greatly increasing a voltage applied to a piezoelectric vibrator and using a fan. An annular atomizing member (1) is provided and ultrasonically vibrates a vibrating plate (12) with a piezoelectric vibrator (11) to atomize a liquid. The atomizing member (1) is elastically sandwiched and held by a casing (3) through a pair of annular elastic rings (2) that are in contact with the atomizing member (1). A maximum facing width in a radial direction between each annular elastic member and one surface of the atomizing member (1) on one side in the radial direction from the center of the atomizing member (1) is 40% of a radial direction width of the piezoelectric vibrator (11) on one side in the radial direction from the center of the piezoelectric vibrator (11).