Operating speed of an image recording apparatus is optimized within the range in which throughput capacity is not decreased, and exposure processing can be performed so that uneven exposure is not generated in a photosensitive material. When operation causing the photosensitive material to be in a nip state or a nip released state is performed during scanning exposure of the photosensitive material with a light beam, assuming that a maximum value of ascent/descent speed is set to W when each roller comes into contact with the photosensitive material or separates from the photosensitive material, an exposure angle is set to .theta., and exposure feeding linear speed is set to V, a drive controlling section sets the ascent/descent speed W to a value determined from an equation of W=V.times.0.004/tan .theta. and performs moving action.