A light scanning device includes a light source outputting a laser beam, a light deflecting unit having a light reflecting unit, the light deflecting unit being adapted to be rotatable about a predetermined axis and scanning an object with the laser beam reflected by the light reflecting unit, a drive controlling unit controlling a deflection angle variation in a vertical direction of the light deflecting unit per unit time so that an interval between scanning lines in the vertical direction by the light deflecting unit is constant, and a driving unit rotationally driving the light deflecting unit in accordance with an rotational angle determined by the driving controlling unit.