The color image forming apparatus comprises a transfer belt device which feeds a transfer member such as a paper and a plurality of image forming units. The image forming units are disposed facing towards the transfer belt device. The transfer belt device, at least in a portion in which the image forming units have been disposed, is arranged such that it is inclined with respect to the ground. Each of the image forming unit forms a desired image and sequentially transfers the formed image on the transfer member fed by the transfer belt device.