A semiconductor pressure sensor (720) includes a thin film piezoelectric element (701) which applies strain to a portion of a semiconductor substrate that corresponds to a thin region (402). The thin film piezoelectric element (701) is formed at a distance away from diffusion resistors (406, 408, 410, and 412) functioning as strain gauges and is extended to the proximity of a bonding pad (716A) connected to an upper electrode layer of the thin film piezoelectric element and a bonding pad (716F) connected to a lower electrode thereof. The diffusion resistors (406, 408, 410, and 412) constitute a bridge circuit by metal wiring (722) and diffusion wiring (724). During self-diagnosis, a prescribed voltage is applied to a thin film piezoelectric element (701). If the output difference of the bridge circuit between before and after the voltage application falls outside a prescribed range, it is determined that a breakage occurs in the semiconductor pressure sensor (720).