A fusing device for thermally fusing a developer image transferred onto a recording sheet comprises: a tubular fusing film; a heating element disposed inside the fusing film; a nip plate disposed in such a manner as to contact with an inner surface of the fusing film and to allow the fusing film to slide along the nip plate; a reflecting plate configured to reflect radiant heat from the heating element toward the nip plate; a backup member configured to nip the fusing film with the nip plate to form a nip portion between the fusing film and the backup member; and a stay configured to support both end portions of the nip plate with respect to a recording sheet conveyance direction. The reflecting plate has a flange portion extending along the recording sheet conveyance direction, and the flange portion is held and supported between the nip plate and the stay.
