The present invention suppresses deterioration of the isolation characteristics. According to the present invention, a first acoustic wave element (a first filter 2) comprises: a first substrate (20),at least a part of which has piezoelectricity; a first functional electrode (21) which is provided on a first surface (20A) of the first substrate (20); and a first wiring conductor (23) which is electrically connected to the first functional electrode (21). The first acoustic wave element (the first filter 2) additionally comprises: a relay electrode (24) which is provided on the first surface (20A) of the first substrate (20) and is electrically connected to a second wiring conductor (33); and a ground electrode 25 which is provided on the first surface 20A of the first substrate 20 and iselectrically connected to the first functional electrode 21. The ground electrode (25) is arranged between the relay electrode (24) and at least one of the first functional electrode (21) and the first wiring conductor (23), while being electrically insulated from the relay electrode (24).