A tandem type color image forming machine comprises a plurality of image forming units, a belt mechanism comprising an endless belt including a linear moving area, and a paper feed cassette in its image information machine body. The image forming units are arranged along the linear moving area of the belt with a space therebetween. The belt mechanism is arranged longitudinally so that the linear moving area of the belt extends almost in the vertical direction. The paper feed cassette is arranged longitudinally in the lateral direction of the belt mechanism or below the belt mechanism.