A color image forming apparatus includes a plurality of image carriers for
at least one color, a plurality of developing devices, each developing a
toner image onto each image carrier, a plurality of charging devices,
each charging the each image carrier, a first power source, connected to
the developing devices in common, a second power source, connected to the
charging devices in common, and a controller, changing a process control
of at least one of the charging devices and the developing devices in
accordance with a color image forming operation and a monochrome image
forming operation.