A print head driving method controls a gradation of a print head employing an array light source of a lower resolution and an array light source of a higher resolution based on image data represented by 2n bits, wherein n is zero or a positive integer, and both of the array light sources are gradation-controlled by combining a pulse weight-application method and a pulse accumulation method. Further, a image formation apparatus controls a gradation of a print head employing an array light source of a lower resolution and an array light source of a higher resolution based on image data represented by 2n bits, wherein n is 0 or a positive integer, and both of the array light sources are controlled by a gradation control method employing a simple combination of a pulse weight-application method and a pulse accumulation method.