A power transmitting device comprising: a power transmitting unit configured to transmit AC transmission power to a power receiving device in a non-contact manner; a first tuner configured to discretely tune a frequency of the transmission power; a second tuner configured to discretely tune a resonance frequency of the power transmitting unit; and a controller configured to control the first tuner to tune the frequency of the transmission power at a first frequency interval, and control the second tuner to tune the resonance frequency at a second frequency interval, wherein the first tuner includes an inverter configured to generate the transmission power and supply the generated transmission power to the power transmitting unit and to tune the frequency of the transmission power, wherein the second tuner includes a capacitor configured to tune the resonance frequency by changing its capacitance, the capacitor being disposed between the inverter and the power transmitting unit, and wherein the controller is configured to set an initial capacitance of the capacitor with starting of power transmission from the power transmitting unit and to control the inverter such that the frequency of the transmission power is tuned, characterized in that the second frequency interval is greater than the first frequency interval, in that it further comprises a position detector configured to detect a positional relationship of a power receiving unit of the power receiving device relative to the power transmitting unit, in that the controller comprises prepared data indicating a relationship between the positional relationship and the capacitance of the capacitor, and in that the controller is configured to set the initial capacitance of the capacitor based on the detection result of the position detector with reference to the data. a power transmitting unit configured to transmit AC transmission power to a power receiving device in a non-contact manner; a first tuner configured to discretely tune a frequency of the transmission power; a second tuner configured to discretely tune a resonance frequency of the power transmitting unit; and a controller configured to control the first tuner to tune the frequency of the transmission power at a first frequency interval, and control the second tuner to tune the resonance frequency at a second frequency interval, wherein the first tuner includes an inverter configured to generate the transmission power and supply the generated transmission power to the power transmitting unit and to tune the frequency of the transmission power, wherein the second tuner includes a capacitor configured to tune the resonance frequency by changing its capacitance, the capacitor being disposed between the inverter and the power transmitting unit, and wherein the controller is configured to set an initial capacitance of the capacitor with starting of power transmission from the power transmitting unit and to control the inverter such that the frequency of the transmission power is tuned, characterized in that the second frequency interval is greater than the first frequency interval, in that it further comprises a position detector configured to detect a positional relationship of a power receiving unit of the power receiving device relative to the power transmitting unit, in that the controller comprises prepared data indicating a relationship between the positional relationship and the capacitance of the capacitor, and in that the controller is configured to set the initial capacitance of the capacitor based on the detection result of the position detector with reference to the data.