To provide a wiring board with the creeping distance between an input part and an output terminal part is extended and the insulation properties can be improved using a simple structure, and to provide a semiconductor relay in which the wiring board is arranged internally.

In the wiring board 10, the input and output terminal parts 21 and 22 for electronic component mounting are formed of conductive materials on an insulating substrate 18, and a surface excepting the input and output terminal parts 21 and 22 is covered with protection films 19. In at least one set of the input and output terminal parts 21 and 22, a groove 31 which is not covered with the protective film 19 is formed between the input and output terminal parts 21 and 22 to constitute an input/output insulation separating part 30.