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 (24) controls such that electricity that a power supply unit (21) supplies reaches a first electricity quantity Pa before a power supply-side communications unit (23) receives a request signal from a vehicle-side communications unit (43), and controls such that electricity that the power supply unit (21) supplies reaches a second electricity quantity Pb, which is greater than the first electricity quantity Pa, after the power supply-side communications unit (23) receives the request signal from the vehicle-side communications unit (43). The vehicle-side communications unit (43) activates on the basis of the first electricity quantity Pa received from the power supply unit (21) of a power supply device (2).