In a developing device adapted to be removably mounted with respect to an image forming apparatus, there are provided protective cover members for covering and protecting a developing sleeve for developing a latent image on an image bearing member and spacer rollers for maintaining the gap between the image bearing member and the developing sleeve at a predetermined distance. Opening-closing of these protective cover members is effected in response to operation of a member such as a handle which is capable of being drawn out with respect to the developing device.