Abstract: Disclosed is a multi-layer wiring board comprising insulating layers of a thermosetting resin having through-holes formed therein, conductor wiring layers buried in the surfaces of said insulating layers, and via-conductors formed by filling said through-holes with an electrically conducting paste, the via-conductors being electrically connected to said conductor wiring layers, wherein coupling layers comprising a silane coupling agent are formed in the interfaces between said conductor wiring layers and said via-conductors or said insulating layers. The multi-layer wiring board features an increased chemical affinity between the conductor wiring layer and the insulating layer, effectively suppressing the infiltration of water through the interface between the conductor wiring layer and the insulating layer or through the insulating resin, and effectively preventing deterioration in the properties under a high-temperature and high-humidity environment of an extended period of time.