A signal transmission circuitry is a circuitry that transmits a signal from a first system on a transmission side to a second system on a reception side. The first system includes an inductor, a first current source controlled by a first switch, a second current source connected in series with the first current source via the inductor and controlled by a second switch, a third switch connected in parallel with the first current source and controlling connection with a ground point, and a fourth switch connected in parallel with the second current source and controlling connection with the ground point.