To realize an excellent heat conductivity and durability by loading this electric heating unit to a water boiler and the like, by laminating three sheets of metal foil heating elements and plural insulating plates at a specific alignment to obtain a heating unit.

This heater unit is composed by laminating the first metal foil heater element 13, the second metal foil heater element 14, and the third metal foil heater element 15, by providing insulating plates 16 between them and at both side surfaces of them to form into a unit. By assembling this unit to an electric water boiler, the following operations can be carried out. The power is fed to the first and the second heater elements 13 and 14 at a time, to boil the water at a high speed in a short time, or the water is boiled normally by only the first heater element 13, and after the water boiling is completed, the temperature of the hot water is kept by the third heater element 15. Since three metal foil heating elements are set centralizing at the bottom surface of a container, the number of parts can be reduced, and the assembly is made easy at a low cost, compared with the conventional water boiler. Furthermore, since it is formed in a unit, the heat transmitting loss inside the heater unit is reduced, and an excellent durability is also obtained.