To prevent large variation in the electrical resistivity of an electronic part and the disconnection of wire even when the electronic part is used in a highly corrosive sulfurizing atmosphere by forming a nickel plated layer on the conductive surface formed on an insulating substrate, in a nickel plating bath having a specified pH value.

A pair conductive Ag-electrode layers 12 is provided at the terminal parts of the upper face, the side faces and terminal parts of the lower face of an insulating substrate 11. A resistive layer 13 is arranged between a pair of Ag-electrode layers 12, each positioning at the terminal part of the upper face of the insulating substrate 11, and, after electrically connecting with one part of each Ag-electrode layer 12, a part of each Ag-electrode layer 12 and the resistive layer 13 are covered with a protective glass film 14. Then, a nickel plated layer 15 is formed on the surface of each Ag-electrode layer 12 provided on the insulating substrate 11, in a nickel plating bath having a pH of 3.6-4.2, and further the nickel plated layer is covered with a metal plated layer 16 having a low melting point. Thereby, the formation of a gap at the interface between the protective glass film 14 and the nickel plated layer 15 can suppressed and the elution of Ag-electrode layers 12 is inhibited.