A sensor includes a sensor electrode layer including a capacitive sensing unit, a first reference electrode layer provided to face a first surface of the sensor electrode layer, and a first elastic layer that is provided between the first reference electrode layer and the sensor electrode layer, and is configured to be elastically deformed by shear force added in an in-plane direction. At least one of the first reference electrode layer or the first elastic layer includes a first probe portion that is displaced in an in-plane direction in accordance with elastic deformation of the first elastic layer, and changes an electrostatic capacitance of the sensing unit.