An object of the present invention is to provide a light deflection device having a simple structure suitable for reducing the size and weight where a deflection angle can be increased. The object can be achieved with a light deflection device including: a light deflection element that deflects incident light in one direct to be emitted; a driving unit that drives the light deflection element; and a diffraction element that is disposed on a light emission side of the light deflection element in which a periodic structure pitch gradually changes from a center of deflection from the light deflection element toward an outside.