A flash fixing device is disclosed. The flash fixing device has a group of main flash lamps which emit main flash light for fixing a toner image on a recording medium; an auxiliary flash lamp provided at a position corresponding to between a pair of flash lamps of the group of main flash lamps; and a light-emission control unit controlling light-emission of the group of main flash lamps and light-emission of the auxiliary flash lamp by using a predetermined relationship. Also disclosed is an image forming device having the flash fixing device.