An acoustic wave device includes a piezoelectric layer and first and second electrodes. The first and second electrodes face each other in a direction crossing a thickness direction of the piezoelectric layer. The acoustic wave device utilizes a bulk wave of a thickness-shear primary mode. The material of the piezoelectric layer is lithium niobate or lithium tantalate. The first and second electrodes include aluminum layers, respectively, on the piezoelectric layer. An orientation direction of a crystal of each of the aluminum layers is a direction orthogonal or substantially orthogonal to a second principal surface on the piezoelectric layer side of each of the aluminum layers.