PURPOSE: To accurately detect the remaining amount of toner near life and to reduce cost by supplying specified amount of toner in the case empty toner is not confirmed and in the case erroneous counting decided result is out of a range.

CONSTITUTION: When an empty toner detection means 1 outputs empty toner to an empty toner confirming means 9, a following erroneous counting deciding means 10 decides that outputted number of supplying times is the correct number of supplying times for empty toner when the value of the number of supplying times at that time is within the previously fixed ranges of the maximum value and the minimum value. In the case the means 9 does not confirm empty toner, and in the case the decided result by the means 10 is out of the range, the specified amount of toner is supplied by a toner supply mechanism 5 without changing the set element of an arithmetic circuit 7. Thus, the number of times of preliminarily announcing empty toner is updated and decided based on the mean value of the newest number of supplying times for empty toner.