An ultrasound unit 30 includes: ultrasound elements 20 each including a plurality of ultrasound cells 10 formed on a substrate 11 including a semiconductor, the plurality of ultrasound cells 10 each including an upper electrode 16 having a ground potential and a lower electrode 12 to which a drive signal is applied, the upper electrode 16 and the lower electrode 12 being arranged facing each other via a cavity 14A and thereby forming a first capacitor 71 a package member 60 in which the plurality of ultrasound elements 20 are disposed, the package member 60 having a ground potential and an insulation member 63 disposed between the package member 60 and each of the ultrasound elements 20. A second capacitor 72 is formed as a result of the insulation member 63 serving as a gap, and a capacity of a third capacitor 73 serially connected to the second capacitor 72 is smaller than a capacity of the second capacitor 72.
