A gradation control system includes a device for deriving 2**n decoded data from lower n bits expressing a gradation per dot, a device for grouping the 2**n decoded data with respect to a plurality of dots, to produce 2**n first bit planes, a device for giving to an element a signal of pattern corresponding to each of the first bit planes for a time obtained by adding a time that depends on a decoded value of each of the first bit planes, to an initializing time, a device for grouping, per bit weight, respective bits excluding the lower n bits that express the gradation per dot, to produce a second bit plane, and a device for giving to the element a signal of pattern corresponding to the second bit plane for a time that depends on a weight of the second bit plane.