An image formation apparatus includes a developing unit for developing
latent image, and a reserve tank that temporarily stores developer ejected
from a first cartridge and a second cartridge and that discharges the
developer to the developing unit. The reserve tank is provided with a
storage amount sensor for sensing storage amount of the developer in the
first reserve tank. The image formation apparatus further includes a
controller for controlling ejection of developer from at least the first
cartridge and the second cartridge into the first reserve tank in
accordance with output from the storage amount sensor.
