A communication system performs wireless communication using electromagnetic field coupling between a transmission coupler and a reception coupler and moves at least one of the transmission coupler and the reception coupler so as to change the position in a predetermined direction of the reception coupler relative to the transmission coupler. In the communication system, the greater the distance between an overlap portion where the transmission coupler and the reception coupler overlap as viewed from a vertical direction to the predetermined direction and an input end of the transmission coupler is, the higher the degree of coupling between the transmission coupler and the reception coupler becomes.