An image forming unit including a toner supplier that comprises a cylindrical conveying passage member and a toner conveying rotational body that is inserted into the cylindrical conveying passage member, includes first/second spiral blades formed on different areas of a rotational axis in an axis direction, wound in directions opposite to each other and is rotated so that the first/second spiral blades convey toner in convergent directions. The rotational axis is inclined such that the second spiral blade is higher than the first spiral blade, and the cylindrical conveying passage member comprises a fresh toner receiving opening that receives fresh toner, a collected toner receiving opening that receives collected toner, and a toner supplier opening disposed at a position where the fresh toner conveyed by the first spiral blade and the collected toner conveyed by the second spiral blade meet, so as to supply the toner to the developer.