A physical quantity sensor includes: a substrate; a first movable body that is provided on the substrate and includes first movable electrode sections; first fixed electrode sections disposed on the substrate so as to face the first movable electrode sections; a second movable body that is provided on the substrate and includes second movable electrode sections; and second fixed electrode sections disposed on the substrate so as to face the second movable electrode sections. A post section protruding from the principal surface of the substrate is provided in a portion of the substrate located between the first and second movable bodies in plan view.