A developing device includes a developing roller, a regulating blade, seal members, and contact members. The regulating blade extends in a rotation axis direction of the developing sleeve, is disposed opposite to a circumferential surface of the developing sleeve, and regulates a quantity of the toner on the circumferential surface of the developing sleeve. The seal members are disposed opposite to the circumferential surface without being in contact with both ends of the developing region in the rotation axis direction. Each contact member is an edge on the developing region side in the rotation axis direction, provided at a position at an upstream side in a rotational direction of the circumferential surface of the developing sleeve relative to an arrangement position of the regulating blade, and configured to be in contact with the circumferential surface of the developing sleeve.