PROBLEM TO BE SOLVED: To provide a technology for solving a defect in hygiene due to contamination of various bacteria derived from an additional cooking pipe. SOLUTION: In order to popularize a "bathing style without additional heating", the structure of an electric heater built-in heat retaining bath 10 is such that an electric heater 12 is disposed between a bath and an adiabatic heat insulating material 19, and the electric heater 12 operates. Is an electric heater built-in heat retention tub 10 in which the electric heater 12 energizes to an arbitrary set temperature and turns on and off within an arbitrarily set energization time setting range only in a bathing mode in which the bath faucet 25 that is electrically linked is closed. Eliminate additional cooking. [Selection diagram] Figure 1【課題】追い炊き配管由来の雑菌汚染による衛生面の不具合点を解決する技術の提供。【解決手段】『追い炊きしない入浴スタイル』の普及を図るため、電気ヒーター内臓保温浴槽１０の構造は浴槽と断熱保温材１９の間に電気ヒーター１２が配設しており、電気ヒーター１２の作動は電気的に連動させた浴槽水栓２５閉止の入浴モード時のみ任意設定した通電時間設定範囲内で電気ヒーター１２が任意設定温度に対して通電しＯＮとなりＯＦＦとなる電気ヒーター内臓保温浴槽１０により追い炊きを無くす。【選択図】図１
