Abstract: A developing material amount detecting apparatus for detecting an amount of developing material contained in a tank includes a detection member provided inside the tank movably between a settled position and a raised position, toner feeding vane for periodically sending the detection member from the settled position to the raised position, and a switch which turns on when the detection member is held substantially in the settled position and turns off when the detection member is held substantially in a position other than the settled position. The apparatus further includes a timer for counting a predetermined time length. The timer starts counting when the switch is turned off. When the switch is maintained off for a time length longer than the predetermined time length, it is indicated that the amount of developing material inside the tank is more than a predetermined amount.