A redundant power supply apparatus includes at least two power inlets, at least two power supply units, and a common component. Each power inlet is connected to an AC power source. Each power supply unit has an input side and the at least two power supply units having a common output side, each input side is connected to the power inlet, and each power supply unit is configured to convert the AC power source into a DC power source. The common component is connected at the common output side and configured to receive DC power sources. Accordingly, the redundant power supply apparatus is provided to improve reliability of redundant operations between multiple external power sources without using mechanical switches.