A speaker 10 includes: a plurality of piezoelectric diaphragms 11 and 12 each including a substrate and a piezoelectric element provided on at least one surface of the substrate; one or a plurality of connecting members 13 connecting the plurality of piezoelectric diaphragms 11 and 12 to each other such that the plurality of piezoelectric diaphragms 11 and 12 aligned from the piezoelectric diaphragm 11 located at a frontmost side of the speaker 10, in a thickness direction of the piezoelectric diaphragm 11, and the piezoelectric diaphragms 11 and 12 adjacent to each other face each other at an interval; a support member 16 supporting the back-side diaphragm 12 that is a piezoelectric diaphragm at a backmost side of the speaker 10. The plurality of piezoelectric diaphragms 11 and 12 include two piezoelectric diaphragms 11 and 12 having stiffnesses different from each other.