A print head being a light-emitting-element-array device for writing data onto a photoreceptor (20K, 20C, 20M, 20Y) by using modulated light, the print head comprising: a light source panel including light emitting elements arranged in a matrix; an optical system array that is an aggregate of optical systems arranged in a matrix shape matched up with the matrix of the light emitting elements, the optical systems each including at least a light-source-side lens and an image-side lens, and the optical systems are configured for focusing light from the light emitting elements onto different regions of the photoreceptor (20K, 20C, 20M, 20Y); and a driver configured to modify light emission amounts of each of the light emitting elements according to the data to be written, the driver including: light receiving elements each including a light receiving surface disposed in a leaked light region and detecting an amount of light incident on the light receiving surface, the leaked light region being in a gap between the light-source-side lens and the image-side lens of each of the optical systems and occupied by optical paths of light transmitted through the light-source-side lenses but not incident on the image-side lenses; and a corrector configured to correct the amounts of light to be emitted from the light emitting elements based on the amounts of light detected by the light receiving elements. a light source panel including light emitting elements arranged in a matrix; an optical system array that is an aggregate of optical systems arranged in a matrix shape matched up with the matrix of the light emitting elements, the optical systems each including at least a light-source-side lens and an image-side lens, and the optical systems are configured for focusing light from the light emitting elements onto different regions of the photoreceptor (20K, 20C, 20M, 20Y); and a driver configured to modify light emission amounts of each of the light emitting elements according to the data to be written, the driver including: light receiving elements each including a light receiving surface disposed in a leaked light region and detecting an amount of light incident on the light receiving surface, the leaked light region being in a gap between the light-source-side lens and the image-side lens of each of the optical systems and occupied by optical paths of light transmitted through the light-source-side lenses but not incident on the image-side lenses; and a corrector configured to correct the amounts of light to be emitted from the light emitting elements based on the amounts of light detected by the light receiving elements. light receiving elements each including a light receiving surface disposed in a leaked light region and detecting an amount of light incident on the light receiving surface, the leaked light region being in a gap between the light-source-side lens and the image-side lens of each of the optical systems and occupied by optical paths of light transmitted through the light-source-side lenses but not incident on the image-side lenses; and a corrector configured to correct the amounts of light to be emitted from the light emitting elements based on the amounts of light detected by the light receiving elements.