An optical deflector includes an oscillating system and a driving system for driving the oscillating system, the oscillating system including a first oscillator, a first torsion spring, a second oscillator, a second torsion spring and a supporting member, the first oscillator including a first movable element having a light deflecting element configured to deflect light, the second oscillator including a second movable element having a mass adjusting member configured to adjust a mass, wherein the first movable element is resiliently supported by the second movable element through the first torsion spring, for torsional oscillation about an oscillation axis, wherein the second movable element is resiliently supported by the supporting member through the second torsional spring, for torsional oscillation about the oscillation axis, and wherein the oscillating system has at least two natural oscillation modes having different frequencies, about the oscillation axis.