The present invention provides a cheap and high-sensitivity semiconductor sensor and method for manufacturing the same. Wherein, the semiconductor sensor includes: a plurality of piezoelectric thin films layered on the semiconductor substrate, a pair of electrodes that are formed at an interface of at least the pair of the piezoelectric thin films layered above and below and excite surface acoustic waves; a metal thin film that is formed at an interface of the lowest-layer piezoelectric thin film and the thin film, and facilitate a growth of a ridge-and-valley portion on a surface of an uppermost-layer piezoelectric thin film of the piezoelectric thin films; and a sensitive film for molecular adsorption formed on at least the ridge-and-valley portion on the uppermost-layer piezoelectric thin film.