PURPOSE: To protect cleaning member and photoreceptor from deformation and damage by detecting the failure in supplying of cleaning liquid to the sliding cleaning member with a detecting member and letting the detection signal thereof prevent a latent image carrier from being driven.

CONSTITUTION: Developer 10, sucked up by a pumpe 11, is supplied to the air contact part of a cleaner blade 9 and photosensitive drum 1 by way of a feed pipe 12 of cleaning liquid. A supply detecting means 13 for cleaning liquid is provided on the way of the abovementioned supply pipe 12 so that in the event of failure in supplying of the cleaning liquid (developer) to the cleaner blade 9 owing to the trouble or the like of the pump 11 this state is detected to avoid driving of the photosensitive drum 1. The above detecting means detecs the presence or not of the supply through combination of, e.g., a light source and a photo detector. This detecting means is let to serve also as a detecting means of the mechanism which automatically controls developer concentration.