An image forming apparatus includes: four image forming units for black, yellow, magenta and cyan respectively, each image forming unit having at least a developing member; and a photosensitive member on which a toner image is formed with either a black toner, a yellow toner, a magenta toner or a cyan toner of each of developing members, and in which the formed toner image is transferred onto a recording material; wherein turbidity of each of the black toner, the yellow toner, the magenta toner and the cyan toner used in each developing member of the four image forming units is less than 60, maximum difference between the turbidities of the black toner, the yellow toner, the magenta toner and the cyan toner is in a range of 5 to 45, the photosensitive member is an amorphous silicon-based photosensitive member, and the black toner has the turbidity of less than 25.