provided are an electric automobile to which a power supply device supplies power , and an electricity supply system capable of accurately associating the power supply device and the electric automobile carrying out communication therewith . a power supply - side control unit controls such that electricity that a power supply unit supplies reaches a first electricity quantity pa before a power supply - side communications unit receives a request signal from a vehicle - side communications unit , and controls such that electricity that the power supply unit supplies reaches a second electricity quantity pb , which is greater than the first electricity quantity pa , after the power supply - side communications unit receives the request signal from the vehicle - side communications unit . the vehicle - side communications unit activates on the basis of the first electricity quantity pa received from the power supply unit of a power supply device .