Method of and apparatus for detecting toner empty

Disclosed are a toner empty detecting method of and a toner empty detecting apparatus for detecting an empty state of toners in a toner hopper. The toner empty detecting method comprises: a step of taking in the output of the detecting element with every constant period; a step of comparing a detected value relative to a take-in value with an average value of the detected values during a detection period of last time; a step of counting the number of times when the detected value is smaller than the average value during a detection cycle of this time; and a step of generating a toner empty output when the count value is larger than the predetermined value. The toner empty detecting apparatus comprises: a toner sensor for detecting the toners in the toner hopper; and a control circuit for comparing a detected value relative to a take-in value when taking in an output of the toner sensor with every constant period with an average value of the detected values during a detection period of last time, comparing the count value with a predetermined value and generating an empty output when the count value is larger than the predetermined value. Even if there is a scatter in output level of the toner detection sensor, the toner empty can be thereby stably detected.