In one embodiment of the present invention, a connecting device of a double-sided wiring board includes a first-side connecting land portion configured by a first-side conductive layer and a first-side connecting conductive layer and a second-side connecting land portion configured by a second-side conductive layer; the first-side connecting land portion and the second-side connecting land portion face each other at respective central portions with an insulating substrate sandwiched therebetween; a substrate hole is formed corresponding to a peripheral end portion of the first-side connecting land portion and a peripheral end portion of the second-side connecting land portion; and the peripheral end portion of the first-side connecting land portion and the peripheral end portion of the second-side connecting land portion are connected to each other via the substrate hole.