A light beam scanner includes a supporting substrate. Fixed electrodes of a first set are provided on the supporting substrate to oppose to each other. A mirror is provided between the fixed electrodes, has torsion bars physically connected to the supporting substrate and a mirror electrode section in end portions of the mirror opposing to the fixed electrodes at least. The mirror rotatably vibrates between an upper position of the one fixed electrode and a lower position thereof by torsion force of the torsion bars and electrostatic force due to the voltage using the torsion bars as a rotation axis, when a voltage is applied between one of the fixed electrodes and the electrode section.