an object of the present invention is to improve an saw propagation velocity v , an electromechanical coupling coefficient , and a delay time temperature coefficient to achieve a high - frequency saw device and power saving and size reduction of the device . an saw device according to the present invention includes at least diamond as a substrate material , a c - axis oriented polycrystalline linbo 3 layer , arranged on the diamond , an sio 2 layer arranged on the linbo 3 layer , and an interdigital transducer and uses an saw in an nth mode . when the thickness of the linbo 3 layer is t 1 , and the thickness of the sio 2 layer is t 2 , kh 1 = 2π and kh 2 = 2π fall within predetermined ranges . in addition , the mode of the saw is selected . with this arrangement , an saw device having a propagation velocity of 7 , 000 m / s or more , an electromechanical coupling coefficient of 2 % or more , and a coefficient tcd of ± 10 ppm /° c . or less , which is the stability of the device frequency with respect to the temperature , can be provided .