A recording section of each of recording heads of different recording colors is divided into a plurality of sub-sections, and the recording heads are moved back and forth relative to a recording medium to conduct a main scan in each run, and thinned images are sequentially recorded on the same area of the recording medium by using different recording sections of the recording heads in a plurality of main scans. The numbers of dots recorded in the main scans are equal without regard to the image data to prevent ununiformity of density due to reach accuracy and amount of discharge and regular ununiformity of color due to a sequence of ink injection.