In an embodiment of the present disclosure, a wiring base includes an insulative base, a signal conductor, a first lead terminal, a first ground conductor, and a second lead terminal. The insulative base includes a first face and a second face. The signal conductor is provided on the first face. The first lead terminal is provided on the signal conductor. The first lead terminal extends in a first direction and includes a portion projecting from the insulative base in plan view toward the first face. The first ground conductor is provided on the second face. The second lead terminal is provided on the first ground conductor. At least a part of the second lead terminal overlaps the first lead terminal in the plan view toward the first face.