An acoustic surface wave transducer with a transmission interdigital electrode (2A) and a reception interdigital electrode (2B) on a piezoelectric surface (1) has been improved by reducing the inband dispersion of frequency characteristics by providing an edge-effect canceller (k,), which cancels an undesired surface wave (E-a) which is generated at the external edge of the extreme end finger (11) of the interdigital electrode (10). The edge-effect canceller is constructed so that the length of the extreme end finger (11) is half of the length of the second extreme end finger (12) of the interdigital electrode, and the spacing between the extreme end finger (11) and the second extreme end finger (12) is 1/2 wavelength of the acoustic surface wave. Thus, the phase of the undesired surface wave (E-a) generated by the extreme end finger (11) of the transmission interdigital electrode is opposite to the wave (E-b) generated by the second extreme end finger (12) and the waves are of equal strength. Hence, those surface waves cancel each other as regards effect on the reception interdigital electrode (28), and the inband deviation or dispersion in the amplitude characteristic and/or the group delay characteristic of the transducer is reduced.