The invention belongs to the technical field of water heaters, and relates to an electric appliance room of a water heater and the water heater. A heat preservation box clamped outside an inner container flange is installed in the electric appliance room, and a vacuum heat insulation panel is arranged in the heat preservation box. According to the electric appliance room of the water heater and the water heater, the heat preservation box is clamped outside the inner container flange, so that the situation that the heat of the inner container flange is seriously dissipated is avoided; meanwhile, the situation that the normal work of electrical components in the electrical appliance room is affected and the subsequent maintenance of the electrical components is inconvenient when a foaming material is used for heat insulation treatment of the electrical appliance room in the prior art is avoided; in addition, the heat preservation box is used for heat insulation treatment of the main heatdissipation end of an inner container, so that the technical problems that the heat dissipation of the main heat dissipation end of the inner container is serious and a traditional heat preservationmaterial occupies large space at the end part are solved.