a fixing apparatus including a pair of rotary members forming a nip for pinching and conveying a recording material , and a rotatable heat supplying member in contact with at least either of the rotary members and supplying the rotary member with heat . an image forming on the pinched and conveyed recording material is fixed thereto by heat , and the rotary member receiving heat from the heat supplying member has different external diameters along the longitudinal direction and the heat supplying member has different plural external diameters so as to follow the shape of the rotary member .