PURPOSE: To provide a cheap electric heater device using far infrared rays by installing a posister heater element or pipe heater element in stoneware fabricated from electromagnetic wave radiative natural stones, or in porcelain made from such natural stones, which are pulverized, mixed, and baked.

CONSTITUTION: A foot warmer or the like for use in an electric 'kotatsu' as Japanese style stove used in a living room, which may be embodied either in framing or recessed in the floor, consists of a posister heater element or pipe heater element built in stoneware or porcelain. The stoneware is fabricated from electromagnetic wave radiative natural stones such as serpentine, while the porcelain is made from such natural stones which are pulverized, mixed, and baked. The device is turned on and off through the action of a timer or a thermostat provided form adjusting the temp. The energy generated from the built-in posister heater and/or pipe heater is accumulated in the stoneware or porcelain and radiated as a soft heat ray of far infrared type to heat various parts effectively. Use of natural stone amplifiers the radiated amount of electromagnetic waves, enhances the effect, allows saving the electric power by 96-88% of usual power consumption, and permits continuous exertion of various functions.