PROBLEM TO BE SOLVED: To provide an electric instant water heating system which can safely control a power amount of a plurality of instant water heaters, and provide excellent energy-saving effect.SOLUTION: An instant water heater 10 is provided with a temperature sensor 11, a flow rate sensor 12, and a control unit 13. A control device 20 is provided with a power estimating means for estimating a power amount consumed at one device. The control device 20 is provided with a power amount calculating means for calculating a total consumed power amount of all the instant water heaters 10 which are in operation. The control device 20 calculates the number of the instant water heater 10 which is available for simultaneous use based on an upper limit power amount. When the number of simultaneously-available devices exceeds the limit, the control device 20 controls the power amount to be consumed.
