A physical quantity sensor includes a base unit as a support substrate, provided with a cavity that is open on one side, a movable unit which is formed on an open side of the cavity and is capable of displacing in a first direction, and spring units that are formed on the open side of the cavity and are connected to the movable unit. A length of the spring units in a second direction that is a direction, which intersects the first direction and in which the base unit overlaps the movable unit, is shorter than a length of the movable unit in the second direction and is longer than a length of the spring units in the first direction.