To reduce the size of a toner supply part, and read an ID of a toner bottle according to a toner supply operation after replacement of the toner bottle without causing toner overflow.

The size of a container that is filled with a toner supplied from a toner bottle 3 is determined to correspond with the maximum amount of toner supplied when the toner bottle 3 is rotated from a reading start position to a reading completion position of an ID pattern. Control means controls to prevent toner from being supplied to the container that is filled with toner in an amount equal to or more than the capacity of the container when toner supply processing and toner bottle ID pattern reading processing are performed at the same time.