A method of manufacturing an acoustic wave element includes simultaneously forming a plurality of electrodes on a piezoelectric substrate, the plurality of electrodes including first and second IDT electrodes and a connection electrode, forming an insulation over the plurality of electrodes and the piezoelectric substrate, the insulation having a first thickness in a direction perpendicular to the surface of the piezoelectric substrate over the second IDT electrode, processing a first portion of the insulation over the first IDT electrode and a second portion of the insulation over the connection electrode to reduce a thickness of the first and second portions of the insulation to a second thickness, and processing a third portion of the insulation over the surface of the second IDT electrode to reduce the first thickness of the third portion to a third thickness, the third thickness being greater than the second thickness.