The present invention discloses a power supply apparatus which is an apparatus installed in an electronic system, and the apparatus includes a DC power input transformer (10) connected with a DC voltage adapter (20) through an electric extension cord (11), such that DC power of different voltage values is rectified into a single voltage value through the DC power input transformer (10) and transmitted to the DC voltage adapter (20) through an electric extension cord (11), and divided into different voltage outputs by the adapter for supplying different voltages to electronic equipments. The invention not only installs the transformer and the adapter at appropriate spaces depending on the spaces of the electronic system, but also supplies DC power with different voltages to different electronic equipments.