A sensor includes an electrode, an insulator, a pressure receiver, and a pressure imparting unit. The insulator is disposed at a position facing the electrode and away from the electrode. The pressure receiver is disposed on a surface of the insulator on a side opposite to the electrode. The pressure imparting unit presses a part of the insulator toward the electrode at a position different from the pressure receiver to contact the insulator with the electrode. The insulator generates power by contact charging or separation charging with respect to the electrode, to output the power as a signal.