An image-forming machine which forms an image on a photosensitive material drum which passes through the steps of electric charging, exposure to light, developing and transfer. A pair of side walls are disposed opposite to each other, spaced at a distance. Inner wheels of bearings have an inner wheel and an outer wheel. The inner wheels are secured to the outer peripheral surfaces of the photosensitive material drum at both ends thereof, and outer wheels of the bearings are secured to the corresponding side walls, so that the photosensitive material drum is rotatably supported by the side walls.