A fixing device configured to heat a recording material bearing a toner image at a nip portion while conveying the recording material includes a tubular film, a nip portion forming member contacting an inner surface of the film, a pressure member forming the nip portion together with the nip portion forming member via the film, and a regulating member configured to regulate a movement of the film by contacting an end surface of the film. The regulating member includes, in a vicinity of the nip portion, a regulating surface inclined such that a distance from an imaginary plane including the end surface is gradually decreased as the regulating surface extends away from the nip portion to a circumferential direction of the film, and that the distance therefrom is gradually increased as the regulating surface extends in a radial direction of the film.