A developing unit includes a developer containing unit that contains developer, a developer carrier that has a moving surface, and carries the developer, a magnetic force generator that attracts the developer onto the moving surface by a magnetic force generated from a plurality of magnets, and a restricting member that restricts a layer thickness of the developer. The magnets includes a restricting magnet arranged closest to the restricting member and has a restricting magnetic pole of which a first surface toward the moving surface and a second surface toward an upstream adjacent magnet that is arranged so as to be adjacent to an upstream side of the developer carrier in a direction of movement of the moving surface and has an upstream adjacent magnetic pole form a ridged corner portion, and the ridged corner portion is chamfered.