A projection apparatus comprises a projection control unit, power supply device and fan. The projection control unit generates an image beam. The power supply device comprises a filter and voltage driving unit. The voltage driving unit is coupled to the filter and comprises a voltage-regulation feedback unit and current amplification component. The filter receives a PWM signal and accordingly outputting a first DC voltage. The voltage-regulation feedback unit receives the first DC voltage and outputs a second DC voltage. The current amplification component is coupled to the voltage-regulation feedback unit for receiving an operational voltage and the second DC voltage, current-amplifying the second DC voltage, and accordingly outputting a driving voltage, which is fed back to the voltage-regulation feedback unit. The voltage-regulation feedback unit regulates the driving voltage according to the first DC voltage. The fan receives the driving voltage for releasing heat of the projection control unit.