An imaging head faces an imaging surface and is relatively moved along the scanning surface in a predetermined scanning direction. The imaging head includes an imaging element group and an alteration section. The imaging element group is structured by a plurality of imaging elements, which are arranged two-dimensionally in a plane substantially parallel to the imaging surface. The imaging element group generates a group of image pixels at the imaging surface in a two-dimensional arrangement which is inclined, as a whole, at a predetermined inclination angle with respect to the scanning direction. The alteration section alters a number of image pixels in a direction which is inclined from the scanning direction by the inclination angle, on the basis of a difference between the predetermined inclination angle of the imaging element group and an actual inclination angle of the image pixel group.