PURPOSE: To ensure low cost with high heat resisting durability, chemical resistance and good workability by inserting a metal washer having specific Vickers hardness and thickness respectively between an enameled substrate and a screw and/or a base material.

CONSTITUTION: When an enameled substrate 1 with the surface thereof applied with enamel is fixed to a base material 2 with a bolt 3, a washer 5 is fitted between the enameled substrate 1 and the head of the bolt 3, and the substrate 1 and the base material 2. In this case, the thickness of the washer 5 is 0.1W1.5mm and made of a metal having Vickers hardness equal to or below 80. According to the aforesaid construction, it is possible to ensure high heat resistance and durability without any crack on the enameled substrate 1 and low cost with good workability.