A wiring board includes a base having extensibility and a wiring formed on the base. The wiring includes a wiring portion and a conductor portion. The wiring portion is formed on the base and extends in a first direction crossing (for example, perpendicular to) a longitudinal direction of the base. The conductor portion is formed on the wiring portion and extends in the first direction. Even when the wiring board is extended along a main extension axis in parallel with the longitudinal direction of the base, change of the resistance of the wiring is prevented. Thus, the wiring board represents stable characteristics.