An electric power supply system includes a battery, an electric power receiving apparatus that is coupled to the battery in parallel with a load and receives and supplies external electric power to the battery, a switching apparatus that allows or cuts off connection of the electric power receiving apparatus and the load to the battery and is switchable between a normal state and a current suppression state when the connection is allowed, and a control apparatus that permits a load driving mode if the external electric power is receivable. In the load driving mode, the control apparatus controls an electrical connection state of the electric power supply system to a first connection state in which the electric power receiving apparatus and the load are coupled to the battery via the switching apparatus in the current suppression state, depending on output electric power of the electric power receiving apparatus.