A fixing device includes a film, a first heat element, a second heat element, a nip member, a reflection member and a supporting member, which are disposed inside a loop of the film, and a pressing member. The nip member contacts the inner circumferential surface of the film. The reflection member surrounds the first heat element with the nip member and reflects radiant heat from the first heat element to the nip member. The pressing member presses the film toward the nip member. The supporting member covers the reflection member, supports the nip member, and includes a first plate portion, a second plate portion and a third plate portion. The second heat element is disposed in at least one of the second plate portion, the third plate portion, one end portion of the nip member, and another end portion of the nip member.