Acoustic wave element, duplexer and communication device

An acoustic wave element comprising:

• a piezoelectric substrate;
• an excitation electrode which is located on an upper surface of the piezoelectric substrate, comprises a plurality of electrode fingers, and generates an acoustic wave;
• and
• two reflectors which are located on the upper surface of the piezoelectric substrate, comprise a plurality of reflector electrode fingers, and sandwich the excitation electrode in the propagation direction of the acoustic wave, wherein
• the excitation electrode comprises
• a main region located between the two end parts of the propagation direction of the acoustic wave and in which electrode finger design of the electrode fingers is uniform, and
• two outer regions which are located on the two sides while sandwiching the main region therebetween and which extend from a part modified in the electrode finger design from that of the main region up to the end parts,
• in the each of the reflectors, a resonant frequency determined according to electrode finger design of the reflector electrode fingers is lower than the resonant frequency determined according to the electrode finger design of the electrode fingers of the main region, and,
• when an interval between the center of two adjacent electrode fingers in the main region is “a”, the number of the electrode fingers configuring one of the outer regions is “m”, and a distance between the center of the electrode finger which is located on the outmost edge of the main region and the center of the reflector electrode finger which is located on the innermost edge of the reflector is “x”,
• 0.5×a×(m+1)<x<a×(m+1) is satisfied.