A developer carrying member is disposed below a storage chamber of a frame and has a surface configured such that a plurality of dielectric portions are dispersed on a conductive portion, an upper region of the storage chamber of the frame is enlarged further in a horizontal direction than a lower region in which the developer carrying member is disposed, and the frame has a lower guide surface and includes a curved surface having a tangent plane inclined at a first angle equal to or greater than a degree of an angle of repose of the developer and less than 90 degrees, in an inner wall of the lower region, and an upper guide surface includes a curved surface having a tangent plane inclined at a second angle that is less than the first angle relative to a horizontal plane in an inner wall of the upper region.