An image recording apparatus (1) causes a recording head (20) to move through a distance corresponding to one half of the recording width of the recording head (20) in a sub-scanning direction each time a recording drum (10) makes one rotation. This, light emitting devices (23, 24) record two line data in advance, and thereafter following light emitting devices (21, 22) record the same line data repeatedly at the same position. This increases the energy of laser light beams given to a recording position on a printing plate (P) to accomplish the recording of an image with reliability. The recording speed is not extremely decreased because not all light emitting devices (21 to 24) are used to make the repeated recordings at the same position on the printing plate (P). Further, the construction of optical systems and driving systems in the image recording apparatus is not complicated.