An acoustic wave device includes: an electrode that is located on a substrate and excites an acoustic wave; and an oxide silicon film that is doped with an element and provided so as to cover the electrode, wherein a normalized reflectance obtained by normalizing a local maximum value of a reflectance when a light is caused to enter an upper surface of the oxide silicon film doped with the element by a reflectance when a light having a wavelength at the local maximum value is caused to enter an upper surface of the substrate directly is equal to or larger than 0.96.
