An image forming apparatus includes a recording head unit in which a plurality of recording heads are arranged in substantially the same direction as the arranging direction of recording elements such that an overlapped region is formed between the heads, a set angle/overlapped region detector which detects the width of the overlapped region of each of the plurality of recording heads from a predetermined test chart printed using the recording head unit, and an image data distributor which distributes image data input to each of the plurality of recording heads, in accordance with the detected width of the overlapped region between the heads. This apparatus achieves an effect of eliminating density unevenness in the head overlapped region only by rough head alignment.