Abstract: Disclosed herein is a method of making a surface structure on a ceramic substrate capable of suppressing diffusion of Ni to an Au plating layer and of reducing the necessary thickness of the Au plating layer. A metallized layer (12), Ni layer (13) and Au layer (14) are formed in this order on a surface of a ceramic substrate (11). The substrate (11) is heated in a non-oxidizing atmosphere to cause an alloying reaction between the Ni layer (13) and the Au layer (14). Thereafter, an Au plating layer (16) is formed on the NiAu alloy layer (15). Since Ni in the NiAu alloy layer is not easily released, diffusion of Ni into the Au plating layer can be suppressed sufficiently. Therefore, the Au plating layer can be small in thickness, generally less than 1 micron.