which will hereinafter be called 34 an indicator 14 34 out of the hopper 1 a toner supply scale 15 being provided on the indicator 14 and a knob 16 screwed through the indicator 14 to a lever 17 fixed to one end of a shaft 18 mounted through the toner supplying member 3 so constructed that the end of the lever 17 is matched to the scale 15 adjusted to an optimum supply amount of the toner a rocking limiting member 19 having a stopper 19a is so fixed to the other end of the shaft 18 that the rocking range of the rockable member 6 is limited at the position where one end of the lever 17 is matched with the scale 15 with the stopper 19a controlling the rotation of the rockable member 6 numeral 20 illustrates a developing unit provided at the lower portion of the toner supply device the operation of the device thus constructed will now be described as shown in fig1 after the knob 16 is unscrewed to loosen it from the indicator 14 the end of the lever 17 is moved along the scale 15 by using the knob 16 to select a predetermined amount of toner to be supplied at the same time the shaft 18 fixed to the lever 17 is accordingly rotated together with the member 19 to coincide the end of the lever 17 with the scale 15 to provide a desired density of a picture and to then fix the knob 16 to the indicator 14 referring to fig3 when a copying operation is conducted in this state the prime mover 11 is rotated to cause the projection 10 to be rotated with the result that the link 4 is rockably rotated around the.