Surface acoustic wave device, surface acoustic wave filter employing same and antenna duplexer, and electronic apparatus employing same

A surface acoustic wave device (10) comprises a substrate (1) containing lithium niobate, a comb type electrode (22) provided on the upper surface of the substrate and consisting of a plurality of electrode fingers (22a), and a protective film (4) having a corrugated upper surface and covering the comb type electrode (22). Assuming the pitch width of the comb type electrode (22) is p, the width of one electrode finger (22a) is p1, the width between the electrode fingers (22a) is p2, and the thickness of the comb type electrode (22) is h, the following relations: p1+p2=p and h/(2p)>=4.5% are satisfied. With such an arrangement, appropriate reflection characteristics are achieved and a surface acoustic wave device (10) having good temperature characteristics and electric characteristics is obtained.