A non-contact power feeding apparatus comprising: - an alternating-current power source comprising a power converter, - a power transmission coil electrically connected to the alternating-current power source, - a power reception coil, - a load electrically connected to the power reception coil, said power reception coil being configured to output an electric power to the load, the electric power being transmitted, by at least magnetic coupling, in a non-contact manner to the power reception coil from the power transmission coil, the non-contact power feeding apparatus comprising further: a coupling coefficient estimator configured to estimate a coupling coefficient between the power transmission coil and the power reception coil; an available output power calculator configured to calculate an available output power that can be output to the load, based on a limit value of a circuit element (101, 102, 201, 202) of a power feeding circuit including the power transmission coil and the power reception coil and on the coupling coefficient; a command value generator configured to generate a command value of the power converter for outputting the available output power to the load, based on the available output power, wherein the power converter is adapted to convert an input electric power and to output the converted electric power to the power transmission coil; and an error range calculator configured to calculate an error range in the coupling coefficient, due to an estimation error of the coupling coefficient estimator, wherein the available output power calculator calculates the available output powers based on a plurality of coupling coefficients included in the error range, respectively, and wherein the command value generator generates the command value based on a smallest available output power among the calculated plurality of available output powers. - an alternating-current power source comprising a power converter, - a power transmission coil electrically connected to the alternating-current power source, - a power reception coil, - a load electrically connected to the power reception coil, said power reception coil being configured to output an electric power to the load, a coupling coefficient estimator configured to estimate a coupling coefficient between the power transmission coil and the power reception coil; an available output power calculator configured to calculate an available output power that can be output to the load, based on a limit value of a circuit element (101, 102, 201, 202) of a power feeding circuit including the power transmission coil and the power reception coil and on the coupling coefficient; a command value generator configured to generate a command value of the power converter for outputting the available output power to the load, based on the available output power, wherein the power converter is adapted to convert an input electric power and to output the converted electric power to the power transmission coil; and an error range calculator configured to calculate an error range in the coupling coefficient, due to an estimation error of the coupling coefficient estimator, wherein the available output power calculator calculates the available output powers based on a plurality of coupling coefficients included in the error range, respectively, and wherein the command value generator generates the command value based on a smallest available output power among the calculated plurality of available output powers.