An inertial sensor includes a substrate, a movable element that swings around a swing axis; and a protrusion that overlaps with the movable element in the plan view and protrudes from the substrate toward the movable element. The protrusion includes a first protrusion and a second protrusion so located as to be farther from the swing axis than the first protrusion, and when the movable element swings relative to the substrate around the swing axis, the first protrusion and the second protrusion come into contact with the movable element at the same time or the first protrusion comes into contact with the movable element and then the second protrusion comes into contact with the movable element.