COLOR IMAGE FORMING APPARATUS

PROBLEM TO BE SOLVED: To provide a color image forming apparatus wherein respective color image carriers are made usable for the same period, and whose cost is low. SOLUTION: The image forming apparatus provided with several electrophotographic image forming stations adaptable to several developing colors including black and which are equipped with the image carrier, an electrifying device, an exposure device, a developing device, a transfer device and a cleaning device, respectively, and which are arranged side by side in a paper carrying direction, is characterized in that, provided that X denotes the reduction ( ) of the film thickness per the traveling distance 1×107mm of the black image carrier, and Y denotes the reduction ( ) of the film thickness per the traveling distance 1×107mm of the image carrier adaptable to other developing colors, the Y and the X are set within an extent shown by the following inequality; 0.5