An acoustic wave device has a substrate and adjacent IDT electrodes. One IDT electrode has a signal connecting bus bar at one side in a direction orthogonal to a propagation direction and is connected to a signal line. A ground bus bar is grounded and located at the other side in the orthogonal direction. The other IDT electrode has a signal connecting bus bar which is located at the other side in the orthogonal direction and is connected to a signal line. A ground bus bar is grounded and located at the one side in the orthogonal direction. The acoustic wave device further has a floating member on the substrate, which is located at a space between the ground bus bar of the IDT electrode and the signal connecting bus bar of the IDT electrode and is not connected to the ground bus bar nor the signal connecting bus bar.