PURPOSE: To suppress the production of a triple transit echo and to improve frequency characteristics with a simple constitution, by setting sizes of each electrode finger and between electrode fingers of electrode components including wave reception electrodes and their cancellation electrodes to a specified value.

CONSTITUTION: On a piezoelectric substrate 11, thin film output IDT (output converter) 10 and an input converter are formed, and electrode components 12 linked with reed-screen shape are formed to the IDT10, and the electrode components 12 are constituted with the 1st∼5th electrode fingers 12a∼12e. The fingers 12a, 12c∼ 12e are connected with equipotential state, a load resistor R is connected between the fingers 12c and 12b, the fingers 12a∼12c constitute wave reception TR, and the fingers 12c∼12e form a cancellation electrode TE. The width of the fingers 12a∼ 12e toward the direction of arrangement X is taken as W1∼W5 and the intervals among the fingers 12a∼12e are taken respectively as g1∼g4, then the relation of equation can be satisfied, allowing to improve the frequency characteristics.