A physical quantity sensor includes a substrate that has a recess that is open toward one side of the substrate, a diaphragm that has a bottom of the recess as part of the diaphragm and undergoes bending deformation under pressure, a piezoresistance device that is disposed in the diaphragm, a coating layer that faces the diaphragm via a cavity, and wiring layers that are disposed between the substrate and the coating layer, and form, along with the substrate and the coating layer, the cavity. Each of the wiring layers contains a metal, and in a plan view, a circumferential edge of the bottom of the recess is closer to the center of the diaphragm than a substrate-side end of an inner wall surface of one of the wiring layers.