Abstract: A developing device having a developing sleeve loosely mounted on the peripheral surface of a cylindrical developing roller. Both end portions of the developing sleeve are pressed against the developing roller by a pair of guide pads so that a part of the developing sleeve keeps contacting the developing roller. The force applied by the the pair of the guide pads to the developing sleeve is in such an extent that driving force of the developing roller is transmitted to the developing sleeve in the portion in which the developing sleeve contacts the developing roller and that the developing sleeve is allowed to rotate in correspondence with the rotation of the developing roller. A blade member for forming a thin layer of toner on the developing sleeve is in contact with the peripheral surface of the developing sleeve. Fine irregularities are formed on the peripheral surface of the developing sleeve so as to hold toners adhered thereto.