PURPOSE: To make it possible to form a uniform and smooth toner layer and to obtain a good picture image by pressing the bent part of a thin platelike elastic member against a toner carrier and making layer thickness control and thereby making layer thickness control by substantially linear contact.

CONSTITUTION: A toner layer thickness controlling member 3 provided in exit side of a toner container 6 in upstream side of developing position is formed of a metallic thin platelike elastic member, and a bent part 3a bent at specified curvature on free end side is brought into contact with the peripheral face of a sleeve 2 at specified pressing force. At the same time, the base end side is extended to the container 6 side at specified approach angle and fixed to the outer wall face of a supporting member 8 formed in the exit part of the container 6. By such a constitution, toner electrostatic charge can be made uniform even when the disturbance of toner charge occurs, and a good picture can be obtained by preventing toner floculation at the time of layer thickness control.