an image forming apparatus including a fixing device to fix a toner image on a recoding medium ; a compressed air generator to generate a compressed air ; an air nozzle to inject the compressed air to separate the recording medium having the fixed toner image from the fixing device ; a first switching unit to switch the air nozzle between injection and termination , which is provided upstream from the air nozzle ; and a buffer unit to retain the compressed air , which is provided upstream from the air nozzle and downstream from the first switching unit .