PURPOSE: To suppress the drift of resistance value even in the heat treatment process to be conducted after the resistance value trimming such as in printed glass trimming, durable surface electrode firing and the like by a method wherein the resistance value trimming of the laser, which non-destructively passes through an over-glazed layer, is conducted twice.

CONSTITUTION: An electrode layer 3 is provided on both ends of an alumina substrate 1 in such a manner that a part of which is overlapped on an under-glazed layer 2. An over-glazed layer 5, which transmits 90% or more of a YAG laser beam, is formed covering the thin film resistance layer 4 provided on the electrode layer 3 in such a manner that both ends of which are overlapped on the electrode layer 3. Then, a resistance value trimming operation is conducted. First, the thin film resistance layer 5 only is cut using a transmission laser beam, and primary resistance value trimming operation is conducted as high as 85 to 95% of the target resistance value in conformity with a rounded-up multiplying factor. Subsequently, a heat treatment is conducted at 600°C or higher using a belt-type continuous firing furnace. Besides, a secondary trimming is conducted, the thin film resistance value 5 only is cut by a transmission laser beam, and a resistance value trimming is conducted as high as to the target resistance value.