Waste toner collecting device, image forming unit equipped with the collecting device, and color image forming apparatus equipped with the collecting device

A waste toner collecting device used in an image forming unit and in a color image forming apparatus using a plurality of the units, has a cleaning device (32) which removes a residual toner from a photosensitive drum (31) of the unit and discharges the removed waste toner from a discharge port (77), and a toner collecting device which has a receiving port (66) detachably connected to the discharge port and a transfer member (68) for transferring the waste toner from the receiving port to a collecting bag of the unit. The collecting device further has a toner plugging preventing device (70) in a connecting portion between the discharge and receiving ports so as to prevent the waste toner from being attached to and accumulated in the connecting portion.