An image-wise exposure apparatus includes a mirror array device comprising a plurality of small mirrors which are two-dimensionally arrayed in two directions normal to each other and a drive mechanism for changing the orientations of the respective small mirrors independently from each other so that light impinging upon each of the small mirrors is reflected selectively in one of a first direction in which the reflected light impinges upon the photosensitive material and a second direction in which the reflected light does not impinge upon the photosensitive material. A control circuit controls the drive mechanism according to an image signal. In the image-wise exposure apparatus, picture element shifting is carried out. There is provided an antireflective mask which limits the effective aperture of each small mirror to a continuous region not longer than 1.5 a/m as measured in a direction in which the picture element shifting operation is carried out, wherein a represents the mirror pitches in the direction of the picture element shifting and m represents the times by which the number of exposure dots are multiplied by the picture element shifting in the direction.