A toner cartridge has a toner-agitating member that agitates the toner to be
supplied
to a developing unit. The toner cartridge has at least a part of a detecting mechanism
that transmits the motion of the agitating member to detect an amount of the remaining
toner in the toner cartridge. The detecting mechanism has a sensor rod. The sensor
rod has one end that rotatably engages the agitating member and the other end to
which a detector is attached. At least a part of the motion-transmitting section
is made of a material that when the part receives a pressure greater than a predetermined
value, the part absorbs the pressure.