PURPOSE: To prevent the generation of uneven images, by providing a means for driving at least one regulating members for layer thickness in the direction transverse or diagonally transverse to the conveying direction of a developer.

CONSTITUTION: When a sleeve 2 rotates in the stage of performing development, a cam 18 rotates simultaneously, and a press contact member 7 oscillates in an arrow B direction. Even when the lump of a toner advances under the member 7, the lump is easily crushed by the member 7, and the deposit of the toner is prevented. The generation of line-like unevenness in a toner layer 15a is thus prevented. Moreover, the toner fed therein receives the leveling effect in the axial line direction of the sleeve by the oscillation of the member 7; therefore, the nonuniformity in the thickness of the toner layer can be removed and the thickness of the layer 15a after the passage through the press contact member is made uniform with high accuracy. If the member 7 is so constituted that the toner is electrified by the friction by the contact of said member with the toner, the toner is electrified efficiently by the oscillation thereof.