To suppress generation of image defects caused by charging failure of an image carrier.

An image forming unit comprises: charging means for charging the surface of a rotatable image carrier; developing means for developing a latent image formed on the surface of the image carrier with developer; first cleaning means for removing the developer not transferred completely by transfer means which transfers the developer to a print medium, and left on the image carrier; and second cleaning means for evenly scattering an external additive of the developer not removed by the first cleaning means and left on the image carrier. The charging means includes: a rotatable charging member which includes an elastic layer including grooves extending in a rotation direction; charging cleaning means contacting with the surface of a conductive layer of the charging member and including a foam cell on its surface layer. The second cleaning means is a rotatable member including a foam cell on its surface layer, and the density of the foam cell of the charging cleaning means is made equal to or more than that of the second cleaning means.