An example wireless power transmitter is configured for wirelessly transmitting a signal to a power receiving apparatus including a first resonance circuit and a load circuit. The first resonance circuit includes a power receiving coil and a first capacitor. The example wireless power transmitter includes a power supply that has a variable oscillation frequency and generates a signal having the oscillation frequency; a second resonance circuit that transmits the signal to the power receiving apparatus; a measuring unit that measures a signal reflection coefficient, the signal reflection coefficient being determined based on magnitude of the signal and magnitude of a signal reflected on the second resonance circuit to the power supply; and a controller that detects a value of the oscillation frequency making the signal reflection coefficient smaller than or equal to a threshold value, and calculates an electromagnetic coupling coefficient between the power transmission coil and the power receiving coil based on the detected value.