The present invention provides a surface acoustic wave sensor that can favorably suppress the flow of a liquid sample onto IDT electrodes. The SAW sensor (1) is provided with a piezoelectric substrate (23), a first IDT electrode (45) and a second IDT electrode (47) that are positioned on the upper surface of the piezoelectric substrate (23) and are separated so as to sandwich a detection part (detection region (23a)) positioned upon the piezoelectric substrate (23), and a cover (25) that spans across the first IDT electrode (45), the second IDT electrode (47), and the detection part so as to form a space (29). On the lower surface of the cover (25), the contact angle of the detection part-facing surface (25b) (the lower surface of a film (35)), which faces the detection part, to the liquid sample is smaller than that of the electrode pair-facing surface (25a) (the lower surface of cover main body (33)), which faces the first IDT electrode (45) and the second IDT electrode (47).
