To provide a wiring board which can efficiently transmit high-frequency electrical signals of 30 GHz or higher to a wiring conductor.

This wiring board includes an insulating base 1 formed of an oxide sintered material containing an Si component of 25-80 mass% in terms of SiO2, a Ba component of 15-70 mass% in terms of BaO, a B component of 1.5-5 mass% in terms of B2O3, an Al component of 1-30 mass% in terms of Al2O3, and a Ca component of 0-30 mass% in terms of CaO, and a wiring conductor 2 formed on the base 1 and having a specific electrical resistance of 2.5 (μΩ cm) or smaller and the ruggedness of the outer surface of 50 μm or smaller.