An electric heater comprising: a substrate; an inner pattern part disposed on one surface of the substrate and connecting a starting point and an ending point thereof; and a first outer pattern part disposed on the one surface of the substrate such that the first outer pattern part is positioned outside the inner pattern part, spaced apart from the inner pattern part, and connecting a starting point and an ending point thereof, wherein the inner pattern part includes: a plurality of inner tracks spaced apart from each other; and a plurality of inner bridges (64, 65) to connect the plurality of inner tracks with each other in series, wherein the first outer pattern part include: a plurality of outer tracks spaced apart from each other; and a plurality of outer bridges (32A, 33A) to connect the plurality of outer tracks with each other in series, and wherein at least one of the plurality of inner tracks is formed to be longer than the outer tracks, characterized in that the electric heater further comprising: a second outer pattern part positioned outside the inner pattern part, connecting a starting point and an ending point thereof, and symmetrical to the first outer pattern part about an imaginary center line extending across the inner pattern part; wherein the inner pattern part, the first outer pattern part and the second outer pattern part are suitable to generate heat independently from each other. a substrate; an inner pattern part disposed on one surface of the substrate and connecting a starting point and an ending point thereof; and a first outer pattern part disposed on the one surface of the substrate such that the first outer pattern part is positioned outside the inner pattern part, spaced apart from the inner pattern part, and connecting a starting point and an ending point thereof, wherein the inner pattern part includes: a plurality of inner tracks spaced apart from each other; and a plurality of inner bridges (64, 65) to connect the plurality of inner tracks with each other in series, wherein the first outer pattern part include: a plurality of outer tracks spaced apart from each other; and a plurality of outer bridges (32A, 33A) to connect the plurality of outer tracks with each other in series, and wherein at least one of the plurality of inner tracks is formed to be longer than the outer tracks, characterized in that the electric heater further comprising: a second outer pattern part positioned outside the inner pattern part, connecting a starting point and an ending point thereof, and symmetrical to the first outer pattern part about an imaginary center line extending across the inner pattern part; wherein the inner pattern part, the first outer pattern part and the second outer pattern part are suitable to generate heat independently from each other. a plurality of inner tracks spaced apart from each other; and a plurality of inner bridges (64, 65) to connect the plurality of inner tracks with each other in series, wherein the first outer pattern part include: a plurality of outer tracks spaced apart from each other; and a plurality of outer bridges (32A, 33A) to connect the plurality of outer tracks with each other in series, and wherein at least one of the plurality of inner tracks is formed to be longer than the outer tracks, characterized in that the electric heater further comprising: a second outer pattern part positioned outside the inner pattern part, connecting a starting point and an ending point thereof, and symmetrical to the first outer pattern part about an imaginary center line extending across the inner pattern part; wherein the inner pattern part, the first outer pattern part and the second outer pattern part are suitable to generate heat independently from each other. a plurality of outer tracks spaced apart from each other; and a plurality of outer bridges (32A, 33A) to connect the plurality of outer tracks with each other in series, and wherein at least one of the plurality of inner tracks is formed to be longer than the outer tracks, characterized in that the electric heater further comprising: a second outer pattern part positioned outside the inner pattern part, connecting a starting point and an ending point thereof, and symmetrical to the first outer pattern part about an imaginary center line extending across the inner pattern part; wherein the inner pattern part, the first outer pattern part and the second outer pattern part are suitable to generate heat independently from each other. a second outer pattern part positioned outside the inner pattern part, connecting a starting point and an ending point thereof, and symmetrical to the first outer pattern part about an imaginary center line extending across the inner pattern part; wherein the inner pattern part, the first outer pattern part and the second outer pattern part are suitable to generate heat independently from each other.