An ultrasound unit 30 includes a plurality of elements 60 each including N cells 9, in each of which a bottom electrode 11A and a top electrode 16A that constitutes a membrane 18 are arranged facing each other with a cavity 13 therebetween, wherein the element 60 has N1 first cells 9A, and N2 (where N1≠N2, N1+N2=N) second cells 9B having higher reception sensitivity and lower transmission sensitivity than the first cells 9A.
