An SAW device including a glass substrate, an LiNbO3 (LT) substrate, and an electrode. When a pitch of the electrode is &lgr;, a thickness of the LT substrate is H, and K equals to 2&pgr;/&lgr;, a product of K and H is at least 0.5 and at most 1.5. Accordingly, a SAW device which can advantageously reduced in size by a reduction in propagation velocity and which is provided with high K2 and an enhanced temperature characteristic as having a good temperature characteristic of the LT substrate.