An image forming apparatus includes an image bearer; a developing device; a transfer device; a waste-developer container; a developer collecting device including a collected-developer conveyor, a waste channel, a reuse channel, and a channel switching member to switch a route between the waste channel and the reuse channel; a switching determiner to determine whether to dispose or reuse collected developer; an operating condition data collector to collect and store operating condition data used as a degradation speed index of developer in the developing device; a determination type selector to select, according to the degradation speed index, one of a first determination type based on an operating amount and a second determination type based on developer replacement data indicating an amount of developer replaced with supplied developer in the developing device; and a switching controller to control the channel switching member according to determination made by the switching determiner.