A plate wave element includes a piezoelectric body, a comb-shaped electrode disposed on an upper surface of the piezoelectric body, and a medium layer disposed on the upper surface of the piezoelectric body so as to cover the comb-shaped electrode. The comb-shaped electrode excites a Lamb wave as a main wave. The medium layer has a frequency temperature characteristic opposite to that of the piezoelectric body. The plate wave element has a preferable frequency temperature characteristic.