A semiconductor pressure sensor includes: a first semiconductor substrate having a surface; an oxide film provided on the surface of the first semiconductor substrate and having a cavity; a second semiconductor substrate bonded to the first semiconductor substrate via the oxide film and having a diaphragm above the cavity; and a piezoelectric device provided on the diaphragm, wherein no recess is provided in the surface of the first semiconductor substrate within a region of the diaphragm, and a stress mitigating groove is provided in the oxide film outside and around the diaphragm.