A heater for use in a fixing apparatus configured to fix an unfixed toner image formed on a recording material to the recording material, the heater comprising: a substrate (31, 71); a plurality of heat generation members (34a to 34c, 74a, 74b) which are formed on a first surface of the substrate (31, 71) and are controllable independently of each other; a first electrode group (39a to 39c, 76a to 76i) which is formed on the substrate and with which a plurality of first power feeding terminals (50aT1, 50aT2, 50bT1, 56a, 56b) provided to the fixing apparatus is in contact, the plurality of first power feeding terminals (50aT1, 50aT2, 50bT1, 56a, 56b) being configured to feed power to the plurality of heat generation members (34a to 34c, 74a, 74b), the first electrode group (39a to 39c, 76a to 76i) being coupled to the plurality of heat generation members (34a to 34c, 74a, 74b) via first conductors (38a-38d); a plurality of temperature detection elements (T1 to T7, T1a to T5a, T1b, t2 to t7) formed on a second surface of the substrate (31, 71), which is on the opposite side of the substrate (31, 71) to the first surface; and a second electrode group (40a to 40e, 79a, 79b) which is formed on the substrate and with which a plurality of second power feeding terminals (51aT1, 51aT2, 51bT1, 51bT2, 51bT3, 57a, 57b) provided to the fixing apparatus is in contact, the plurality of second power feeding terminals (51aT1, 51aT2, 51bT1, 51bT2, 51bT3, 57a, 57b) being configured to feed power to the plurality of temperature detection elements (T1 to T7, T1a to T5a, T1b, t2 to t7), the second electrode group (40a to 40e, 79a, 79b) being coupled to the plurality of temperature detection elements via second conductors (36a-36d), at least an electrode of the first electrode group and at least an electrode of the second electrode group are formed in a region nearer to one edge portion (31e1, 71e1) of the substrate (31, 71) than to the center of the substrate (31, 71) in a longer-side direction of the substrate (31, 71), wherein the first electrode group is formed on the first surface of the substrate, the second electrode group is formed on the second surface of the substrate, the electrode of the first electrode group formed in the region nearer to the one edge portion of the substrate is provided at a position nearer to the one edge portion than the electrode of the second electrode group formed in the region nearer to the one edge portion of the substrate, and the electrode that is nearest to the second electrode group in the longer-side direction among the first electrode group, which is formed in the region nearer to the one edge portion, and the second electrode group are provided with a space there between in the longer-side direction of the substrate. a substrate (31, 71); a plurality of heat generation members (34a to 34c, 74a, 74b) which are formed on a first surface of the substrate (31, 71) and are controllable independently of each other; a first electrode group (39a to 39c, 76a to 76i) which is formed on the substrate and with which a plurality of first power feeding terminals (50aT1, 50aT2, 50bT1, 56a, 56b) provided to the fixing apparatus is in contact, the plurality of first power feeding terminals (50aT1, 50aT2, 50bT1, 56a, 56b) being configured to feed power to the plurality of heat generation members (34a to 34c, 74a, 74b), the first electrode group (39a to 39c, 76a to 76i) being coupled to the plurality of heat generation members (34a to 34c, 74a, 74b) via first conductors (38a-38d); a plurality of temperature detection elements (T1 to T7, T1a to T5a, T1b, t2 to t7) formed on a second surface of the substrate (31, 71), which is on the opposite side of the substrate (31, 71) to the first surface; and a second electrode group (40a to 40e, 79a, 79b) which is formed on the substrate and with which a plurality of second power feeding terminals (51aT1, 51aT2, 51bT1, 51bT2, 51bT3, 57a, 57b) provided to the fixing apparatus is in contact, the plurality of second power feeding terminals (51aT1, 51aT2, 51bT1, 51bT2, 51bT3, 57a, 57b) being configured to feed power to the plurality of temperature detection elements (T1 to T7, T1a to T5a, T1b, t2 to t7), the second electrode group (40a to 40e, 79a, 79b) being coupled to the plurality of temperature detection elements via second conductors (36a-36d), at least an electrode of the first electrode group and at least an electrode of the second electrode group are formed in a region nearer to one edge portion (31e1, 71e1) of the substrate (31, 71) than to the center of the substrate (31, 71) in a longer-side direction of the substrate (31, 71), wherein the first electrode group is formed on the first surface of the substrate, the second electrode group is formed on the second surface of the substrate, the electrode of the first electrode group formed in the region nearer to the one edge portion of the substrate is provided at a position nearer to the one edge portion than the electrode of the second electrode group formed in the region nearer to the one edge portion of the substrate, and the electrode that is nearest to the second electrode group in the longer-side direction among the first electrode group, which is formed in the region nearer to the one edge portion, and the second electrode group are provided with a space there between in the longer-side direction of the substrate.