A
signal transmission device has a
signal-side
electrode, a first
signal line connected to one side of the signal-side
electrode, a second signal line connected to the other side of the signal-side
electrode, a power supply-side electrode connected to the signal-side electrode via an
electronic component including at least an inductive component, and a
capacitive coupling portion that capacitively couples the power supply-side electrode and a ground wiring or a power supply wiring, the first signal line, the signal-side electrode, and the second signal line forming a transmission path that transmits an
electric signal, and the first signal line and the second signal line transmitting
electric power via the signal-side electrode, the
electronic component, and the power supply-side electrode.