A power supply system includes a first energy storage, a second energy storage, a power transmission circuit, and circuitry. An electrical load is connected to the first energy storage and to the second energy storage via the power transmission circuit. The circuitry is configured to control the power transmission circuit such that the first energy storage charges the second energy storage and supplies electric power to the electrical load according to a demand of the electrical load when a charge rate in the second energy storage is lower than or equal to a first threshold. The circuitry is configured to control the power transmission circuit such that at least the first energy storage among the first energy storage and the second energy storage supplies electric power to the electrical load according to the demand when the charge rate is higher than the first threshold.