A voltage generating apparatus for a headphone is provided, which includes a voltage generator, a charge pump circuit, an operating amplifier and a controller. The voltage generator generates a first operating voltage. The charge pump circuit receives the first operating voltage and an adjusting signal, and generates a second operating voltage according to the first operating voltage and the adjusting signal. The operating amplifier receives the first operating voltage and the second operating voltage serving as the operating voltages thereof and receives an input signal so as to generate an output signal. The controller receives the second operating voltage and a control signal, and generates the adjusting signal according to the second operating voltage and the control signal.