PURPOSE:To improve the usableness of ''kotatsu'' by a method wherein the controlling circuit of a heating elenent and the operating part for instruction are separately provided and the instruction from the operating part to the controlling part is given by way of wireless signal. CONSTITUTION:A transmitting part A containing an oscillator, batteries and a transmitting antenna is arranged within a table board 1 and the operating parts 2 are arranged at a plurality of positions (for example, at four positions) on the sides of the table board 1. The heating element 6 is provided at the center beneath the setting frame 4 of the framed ''kotatsu'' covered with a coverlet 3 placed under the table board 1. The receiving part B containing a receiving antenna, an amplifier, a frequency-to-voltage converter, a detector, a temperature sensor and the controlling circuit of the heating element 6 is arranged near the heating element 6. The frequency of the oscillator in the transmitting part A is changed by operating the operating part 2.
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