The present invention relates to an acoustic wave device including: a substrate; an IDT arranged on the substrate; a connection electrode arranged on the substrate and electrically connected to the IDT; a side wall formed outside the IDT to create a cavity including the IDT on the substrate; a cover formed on a top of the side wall; a connection terminal penetrating the side wall or the cover or formed along an inner or outer peripheral surface of the side wall, and electrically connected to the connection electrode; and a conductive layer formed on a top of the cover not to be overlapped with the connection terminal, in which an area of the conductive layer is less than 50% of an area of the cover.