Control apparatus of an electric vehicle controls a power supply system of the electric vehicle equipped with a first direct current power supply apparatus for supplying direct current power to a traction inverter, and a second direct current power supply apparatus connected in parallel with the first direct current power supply apparatus via a DC/DC converter. This control apparatus is also provided with a relay for cutting off supply of power from the first direct current power supply apparatus to the traction inverter in synchronization with the operation of the self-protection circuit in the event that the self-protection circuit of the traction inverter operates as a result of overcurrents supplied by the first direct current power supply apparatus.