A transmitting device having plural transmitting antennas, the transmitting device comprising: one transmission power supply for outputting electric power, whose frequency matches a resonance frequency of each of the transmitting antennas, on a basis of input power; plural switches respectively provided for the transmitting antennas, the switches being switchable in such a way as to connect or disconnect supply lines for supplying the electric power outputted by the transmission power supply to the transmitting antennas; a parameter detecting unit (122, 123, 124) comprised of a function of preventing breakage of the transmission power supply, the function being included by the transmission power supply, for detecting parameters regarding the transmission power supply, the parameters being changed as a receiving antenna of a receiving device gets close to the transmitting antennas; and a switch control unit for estimating a position of the receiving antenna from a result of the detection performed by the parameter detecting unit (122, 123, 124), and for performing switching control on the switches in accordance with the position of the receiving antenna, wherein the transmitting device includes a matching circuit for matching impedance of the transmission power supply to that of each of the transmitting antennas, and wherein when the estimated position of the receiving antenna extends over those of two or more of the transmitting antennas, the switch control unit switches the switches in such a way as to connect the supply lines of the two or more of the transmitting antennas and causes the matching circuit to control a phase difference of the electric power outputted to the two or more transmitting antennas. one transmission power supply for outputting electric power, whose frequency matches a resonance frequency of each of the transmitting antennas, on a basis of input power; plural switches respectively provided for the transmitting antennas, the switches being switchable in such a way as to connect or disconnect supply lines for supplying the electric power outputted by the transmission power supply to the transmitting antennas; a parameter detecting unit (122, 123, 124) comprised of a function of preventing breakage of the transmission power supply, the function being included by the transmission power supply, for detecting parameters regarding the transmission power supply, the parameters being changed as a receiving antenna of a receiving device gets close to the transmitting antennas; and a switch control unit for estimating a position of the receiving antenna from a result of the detection performed by the parameter detecting unit (122, 123, 124), and for performing switching control on the switches in accordance with the position of the receiving antenna, wherein the transmitting device includes a matching circuit for matching impedance of the transmission power supply to that of each of the transmitting antennas, and wherein when the estimated position of the receiving antenna extends over those of two or more of the transmitting antennas, the switch control unit switches the switches in such a way as to connect the supply lines of the two or more of the transmitting antennas and causes the matching circuit to control a phase difference of the electric power outputted to the two or more transmitting antennas.