Provided is a planar heater device excelling in responsiveness, and capable of preventing a material loss, and obviating the need of a special correction structure for preventing drift. In this planarheater device 2, a plurality of heating surfaces 41 of a heating wire are arranged in parallel with one another on the surface of a support plate 3 by winding the single ribbon-like heating wire 4 onthe support plate 3. The support plate 3 is so structured that ridge-shaped uneven parts 31a are repeatedly formed at pitches P at one of parallel sides thereof opposite to each other; and ridge-shaped uneven parts 31b having the same shapes are repeatedly formed at the same pitches P on the other of the parallel sides by shifting them by 1/2 pitch. By winding the single ribbon-like heating wire4 along ridge-shaped slope faces of the ridge-shaped uneven parts 31a, and by arranging it between the ridge-shaped uneven parts 31a and 31b on both the sides opposite to each other as shown in Fig.,the heating surfaces 41 of the ribbon-like heating wire 4 are set parallel with the surface of the support plate 3, and the plurality of the heating surfaces 41 are arranged in parallel with one another on the support plate surface.