A fixing device includes: a fusing member; a heater; a nip member; a reflection member; a stay; and a backup member. The fusing member has an inner peripheral surface defining an internal space and is circularly movable. The inner peripheral surface is in sliding contact with the nip member. The reflection member reflects a radiant heat from the heater toward the nip member. The reflection member includes a reflection portion and an extending portion. The stay covers the reflection portion and supports the nip member. The extending portion extends outside of the stay. The backup member provides a nip region in cooperation with the nip member upon nipping the tubular flexible fusing member between the backup member and the nip member. The extending portion extends between the nip member and the stay. The extending portion is positioned exclusively downstream of the reflection portion in a sheet feeding direction.