A fixing device for fixing a toner image on a recording medium, comprising: an endless belt-shaped fixing member rotating in a predetermined direction of rotation, formed in a loop; a pressing member contacting an outer circumferential surface of the fixing member to form a nip between the pressing member and the fixing member through which the recording medium bearing the toner image passes; wherein the fixing device further comprises: a laminated heater facing an inner circumferential surface of the fixing member to heat the fixing member; and a heater support provided inside the loop formed by the fixing member to support the laminated heater, the laminated heater provided between the fixing member and the heater support, and comprising a flexible, first heat generation sheet (22s; 22s1; 22s2) having a predetermined length in a circumferential direction of the fixing member and a width in an axial direction of the fixing member, the first heat generation sheet (22s; 22s1; 22s2) comprising: an insulating base layer; at least one resistant heat generation layer (22b; 22b1, 22b2) provided on the base layer to generate heat; and at least one electrode layer provided on the base layer to supply power to the at least one resistant heat generation layer, characterised in that the laminated heater includes a plurality of heat generation sheets (22s1; 22s2) layered in a thickness direction, wherein the resistant heat generation layer (22b1) of the first heat generation sheet (22s1) is shifted from the resistant heat generation layers (22b2) of the second heat generation sheet (22s2) in the axial direction of the laminated heater. an endless belt-shaped fixing member rotating in a predetermined direction of rotation, formed in a loop; a pressing member contacting an outer circumferential surface of the fixing member to form a nip between the pressing member and the fixing member through which the recording medium bearing the toner image passes; wherein the fixing device further comprises: a laminated heater facing an inner circumferential surface of the fixing member to heat the fixing member; and a heater support provided inside the loop formed by the fixing member to support the laminated heater, the laminated heater provided between the fixing member and the heater support, and comprising a flexible, first heat generation sheet (22s; 22s1; 22s2) having a predetermined length in a circumferential direction of the fixing member and a width in an axial direction of the fixing member, the first heat generation sheet (22s; 22s1; 22s2) comprising: an insulating base layer; at least one resistant heat generation layer (22b; 22b1, 22b2) provided on the base layer to generate heat; and at least one electrode layer provided on the base layer to supply power to the at least one resistant heat generation layer, characterised in that the laminated heater includes a plurality of heat generation sheets (22s1; 22s2) layered in a thickness direction, wherein the resistant heat generation layer (22b1) of the first heat generation sheet (22s1) is shifted from the resistant heat generation layers (22b2) of the second heat generation sheet (22s2) in the axial direction of the laminated heater. a laminated heater facing an inner circumferential surface of the fixing member to heat the fixing member; and a heater support provided inside the loop formed by the fixing member to support the laminated heater, the laminated heater provided between the fixing member and the heater support, and comprising a flexible, first heat generation sheet (22s; 22s1; 22s2) having a predetermined length in a circumferential direction of the fixing member and a width in an axial direction of the fixing member, the first heat generation sheet (22s; 22s1; 22s2) comprising: an insulating base layer; at least one resistant heat generation layer (22b; 22b1, 22b2) provided on the base layer to generate heat; and at least one electrode layer provided on the base layer to supply power to the at least one resistant heat generation layer, characterised in that the laminated heater includes a plurality of heat generation sheets (22s1; 22s2) layered in a thickness direction, wherein the resistant heat generation layer (22b1) of the first heat generation sheet (22s1) is shifted from the resistant heat generation layers (22b2) of the second heat generation sheet (22s2) in the axial direction of the laminated heater. an insulating base layer; at least one resistant heat generation layer (22b; 22b1, 22b2) provided on the base layer to generate heat; and at least one electrode layer provided on the base layer to supply power to the at least one resistant heat generation layer, characterised in that the laminated heater includes a plurality of heat generation sheets (22s1; 22s2) layered in a thickness direction, wherein the resistant heat generation layer (22b1) of the first heat generation sheet (22s1) is shifted from the resistant heat generation layers (22b2) of the second heat generation sheet (22s2) in the axial direction of the laminated heater.