The optical scanning device includes a photoreceptor, a light source unit, a plurality of correction value storage units and a light quantity correction unit. The scanning position in the photoreceptor is divided into a plurality of areas. The target correction amount of the light quantity is predetermined so as to change according to the scanning position. The correction value storage unit stores the light quantity correction value that is associated with each of the areas. The light quantity correction unit corrects the light quantity during scanning by using the light quantity correction value corresponding to the scanning position. The length of each of the areas is shorter in an area in which the variation in the target correction amount per unit length is greater. The light quantity correction value is determined based on the target correction amount according to the area corresponding to the light quantity correction value.