A projection apparatus including an illumination unit, a brightness detection circuit, a signal conversion circuit, and a control unit is provided. The illumination unit generates a light source according to a plurality of driving signals and provides a temperature sensing signal according to the temperature of the light source. The brightness detection circuit generates a plurality of brightness sensing signals. The signal conversion circuit converts the temperature sensing signal and the brightness sensing signals into temperature information and a plurality of brightness information. The control unit comprises a setting table for storing a predetermined temperature information and a plurality of predetermined brightness information, and the control unit adjusts the driving signals in order to identify the converted temperature information and the converted brightness information conform to the stored information in the setting table.