An optical device includes a mass section in a plate shape including a light reflector with light reflectivity, a supporting section for supporting the mass section, a pair of elastic sections with elastic deformability for coupling the mass section to the supporting section in a pivotally movable manner, and a driving unit for pivotally moving the mass section, the driving unit including a magnetic section provided to the mass section, magnetized in a direction perpendicular to a surface of the mass section, a pair of magnetic poles with different polarities, provided in a manner to face each other in a direction perpendicular to a pivotal movement central axis with the magnetic portion intervened on the basis of a top view of the mass section in a non-driven condition, and a magnetic field generator having a coil for generating a magnetic force between the pair of magnetic poles. The mass section is pivotally moved upon torsional deformation of the elastic section by operating the driving unit so that a direction of light reflected by the light reflector is changeable. The magnetic generator is structured in a manner to generate a magnetic field between the pair of magnetic poles by applying a voltage to the coil to pivotally move the mass section with respect to the supporting section.