A surge protective apparatus of a power conversion circuit includes an AC-to-DC conversion circuit and two voltage clamping units. The AC-to-DC conversion circuit receives an AC power source and converts the AC power source into a DC power source. The DC power source is provided between a positive output terminal and a negative output terminal of the AC-to-DC conversion circuit. Two first ends of the two voltage clamping units are respectively coupled to a first AC terminal and a second AC terminal of the AC power source, and two second ends of the two voltage clamping units are commonly coupled to the positive output terminal or the negative output terminal. Accordingly, it is to effectively suppress surge energy generated from the AC power source.