According to one embodiment, a method of damping an actuator to reduce an amplitude of a resonance peak of the actuator, including a piezoelectric element and a translation mechanism, includes securing one surface of a restraint member having at least two surfaces to a movable part of the translation mechanism with an elastic or viscoelastic body therebetween, securing the other surface of the restraint member to a support portion of the translation mechanism with an elastic or viscoelastic body therebetween, and converting vibration energy of the movable part into thermal energy, based on distortion caused by deformation of the elastic or viscoelastic body.