PURPOSE: To stop the permanent deformation of fibers to extend the life of a brush considerably, by lowering the rotation speed of the conductive brush of a brush electrostaic charging device temporarily after the electrostatic charging operation to bend fibers in the opposite direction.

CONSTITUTION: While a control signal 7 is supplied to a motor driving control circuit 9, a high-speed driving signal 22 is outputted to rotate a motor 21 in the direction opposite to the rotation direction of a photosensitive drum 2 in a speed 2W5 times as high as the rotation speed of the drum 2, and the drum 2 is charged electrostatically with a conductive brush 1 having 30mm diameter. When the control signal 7 is broken, a low-speed driving signal 22 is outputted from the control circuit 9, and the peripheral speed of the brush 1 is made lower than that of the drum 2. Consequently, the bending direction of brush fibers is opposite, and the elasticity is restored. Therefore, the permanent deformation of fibers is difficult to generate, and the number of copies, which is obtained by the time when the diameter of the brush becomes 26mm to replace the brush, is increased, and the life of the brush is extended considerably.