PURPOSE: To facilitate the miniaturization of an air bridge by burying back the openings of an underside resist layer by metal plating processing provided for forming the posts of the air bridge, and flattening the surface of the resists layer.

CONSTITUTION: Openings 5a for forming the posts P of an air bridge B are provided, by applying resist on a plating conductive layer 4 and forming an underside resist layer 5, and performing the patterning of this underside resist layer 5 after that. Following this, the openings 5a are buried by performing metal plating processing using Au, etc., by an amount corresponding to the thickness of the lowerside resist layer 5 and the surface of this lowerside resist layer 5 is flattened. Furthermore, a second plated conductive layer 7 which covers the underside resist layer 5 and the plated metal 6 wholly is deposited. Next the upperside resist layer 8 is formed on this plated conductive layer 7, and the patterning of the upperside resist film 8 is performed after that. Consequently, openings 8a corresponding to the air bridge are formed in the upperside resist layer 8.