The present invention provides an electrode device, semiconductor device and a semiconductor system capable of accuracy detecting an object to be detected. According to one embodiment, the electrode device 11 is used for detecting the capacitance of the mutual capacitance system, and includes a reception electrode PR1, a transmission electrode PX1 arranged to face the reception electrode PR1, a transmission electrode PX2 arranged to face the reception electrode PR1 with the transmission electrode PX1 interposed therebetween, and a dielectric board 101 provided between the transmission electrode PX1 and the transmission electrode PX2 to fix the distance and the dielectric constant between the transmission electrode PX1 and the transmission electrode PX2.