A developing cartridge includes a developing roller 210d that develops, by way of a developer, an electrostatic latent image that is formed on an image bearing member 207; a developer regulating member that regulates the thickness of a developer carried on the developing roller 210d; and a frame 214a that rotatably supports the developing roller 210d and supports the developer regulating member. The frame 214a has a developing roller support section 214a1 that rotatably supports an outer peripheral face 210d6 of at least one end of the developing roller 210d. The developing roller support section 214a1 has a clearance at a position that, when viewed in the axial direction of the developing roller 210d, overlaps a contact region at which the developing roller 210d is in contact with the image bearing member 207.

A developing device includes a cylindrical developing roller, a regulation member, a magnetic member, and a synthetic resin member. The regulation member includes a first opposing surface facing an outer circumferential surface of the developing roller. The magnetic member is arranged on a side surface of the regulation member. The synthetic resin member is arranged on a side surface of the magnetic member. The synthetic member includes a second opposing surface facing the outer circumferential surface of the developing roller. The second opposing surface is tilted at 40 or more but 60 or less with respect to the first opposing surface to be increasingly distant from the outer circumferential surface of the developing roller toward an upstream side in a rotating direction of the developing roller. A solubility parameter of a material of the synthetic resin member is 23 (J/cm.sup.3).sup.1/2 or more. Magnetic toner contains toner and resin fine particles.