PURPOSE: To obtain a surface material of a plane warmer, which keeps the wiring pattern of a heating wire from being clearly observed from the surface and can be produced at a high efficiency in view of time and cost without restraint in designing the surface material.

CONSTITUTION: A plane warmer consists of a surface material 2, a heating wire 3 and a backing material 4 and they are laminated to form warmer. The surface material 2 has recessed stripes formed due to the differences in the pile lengths. The heating wire 3 in laid on the backing material 4 and covered with the surface material 2. The recessed stripes of the surface material 2 are close to the heater wire 4, their widths is narrower than the pitches of the wiring pattern of the heating wire 4, and the total length of the recessed stripes within a part of the surface material 2 that covers the wiring area of the heater wire 4 is equal to or longer than the length of the heating wire 4, so that the surface material 2 keeps the wiring pattern of the heating wire 4 from being clearly observed from the surface.