In an image recording apparatus disclosed by this invention, a recording medium is conveyed to a recording head having recording unit groups each in which a plurality of the recording units for recording an image are arranged at a predetermined interval linearly at a predetermined angle with respect to a predetermined direction. When the recording medium is conveyed at a predetermined average velocity, an image recording start timing of each recording column is controlled with the recording units contained in a direction intersecting with the predetermined direction of the recording head as a recording column so as to form a linear dot string having an angle different from the predetermined angle in the recording medium by means of the respective recording units of the recording head.