To reduce an insertion loss and also to obtain a transversal filter where a characteristic inside the pass band is improved by adopting one of input/output IDTs as a floating electrode-type internal reflection one directivity IDT and superimposing a TTE mode on a uni-modal filter characteristic.

Input IDT2 and output IDT3 are provided on the main surface of a crystal substrate 1, the distance L is obtained between input/output IDTs 2 and 3 and the electrode configuration of input/output IDTs2 and 3 is an FEUDT configuration providing a floating electrode. Then distance L is the inter-center one L of electrode fingers 7 and 8 which is at the innermost side within input/output IDT2 and 3 being concerned in exciting and receiving except the floating electrode and it is properly selected. Thus, the insertion loss is reduced and, at the same time, the distance L between the two IDT electrode fingers 7 and 8 is minutely set so as to superimpose the ripple of TTE on the transversal filter uni-modal characteristic so that the pass band is made flat.